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Pregnancy and Birth
PREGNANCY AND BIRTH
One of the greatest dramas in the world of living things is that which takes place in pregnancy and birth. Pregnancy forms a bond between mother and offspring that, in humans at least, lasts throughout life. Humans and many other animals are viviparous, meaning that offspring develop inside the mother's body and are delivered live. By contrast, birds and some other varieties of animal are oviparous, meaning that they deliver offspring in eggs that must develop further before hatching. In the modern world, human females experience birth in several ways—vaginal or cesarean, with anesthetics and without, at home or in a hospital—but just a few hundred years ago, there was little variety in an experience that was almost always painful and dangerous.
HOW IT WORKS
Oviparity, Viviparity, and Ovoviviparity
The birth of live offspring is a reproductive feature shared by mammals, some fishes, and selected invertebrates, such as scorpions, as well as various reptiles and amphibians. Animals who give birth to live offspring are called viviparous, meaning "live birth." In contrast to viviparous animals, other animals—called oviparous, meaning "egg birth"—give birth to eggs that must develop before hatching. Finally, there are ovoviviparous animals, or ones that produce eggs but retain them inside the female body until hatching occurs, so that "live" offspring are born.
Oviparous animals may fertilize their eggs either externally or internally, though all animals that fertilize their eggs externally in nature are oviparous. (See Sexual Reproduction for more about internal and external fertilization.) In cases of internal fertilization, male animals somehow pass their sperm into the female: for example, male salamanders deposit a sperm packet, or spermatophore, onto the bottom of their breeding pond and then induce an egg-bearing (or gravid) female to walk over it. The female picks up the spermatophore and retains it inside her body, where the eggs become fertilized. These fertilized eggs later are laid and develop externally. Oviparous offspring undergoing development before birth obtain all their nourishment from the yolk and the protein-rich albumen, or "white," rather than from direct contact with the mother.
Ovoviviparity is common in a wide range of animals, including certain insects, fish, lizards, and snakes, but it is much less typical than oviparity. Ovoviviparous insects do not supply oxygen or nourishment to their developing eggs; they merely give them a safe brooding chamber for development. Nonetheless, species of ovoviviparous fish, lizards, and snakes appear to provide some nutrition and oxygen to their growing offspring. Because nutrition is provided in these instances, some zoologists consider them examples of true live birth, or viviparity.
Viviparity is the type of birth process that takes place in most mammals and many other species. Viviparous animals give birth to living young that have been nourished in close contact with their mothers' bodies. The offspring of both viviparous and oviparous animals develop from fertilized eggs, but the eggs of viviparous animals lack a hard outer covering, or shell. Viviparous young grow in the adult female until they are able to survive on their own outside her body. In many cases, the developing fetuses of viviparous animals are connected to a placenta, a special membranous organ with a rich blood supply that lines the uterus in pregnant mammals. It provides nourishment to the fetus through a supply line called an umbilical cord.
All mammals, except for the platypus and the echidnas, are viviparous; only these two unusual mammals, called montremes, lay eggs. (See Speciation for more about mammal species.) Some snakes, such as the garter snake, are viviparous, as are certain lizards and even a few insects. Ocean perch, some sharks, and a few popular aquarium fish are also viviparous. Even certain plants, such as the mangrove and the tiger lily, are described as viviparous because they produce seeds that germinate, or sprout, before they become detached from the parent plant.
From Zygote to Fetus
The essays on Reproduction and Sexual Reproduction discuss the basics of the reproductive process through the point of fertilization. A fertilized egg is called a zygote, but once it begins to develop in the uterus or womb, it is known as an embryo and later, when it begins to assume the shape typical of its species, a fetus. In the uterus, the unborn offspring receives nutrients and oxygen during the period known as gestation, which extends from fertilization to birth. (In humans the gestation period is nine months.)
The zygote forms in one of the mother's fallopian tubes, the tubes that connect the ovaries with the uterus. It then travels to the uterus, where it becomes affixed to the uterine lining. Along the way, the zygote divides a number of times, such that by the time it reaches the uterus it consists of about 100 cells and is called an embryoblast. The exact day on which the embryoblast implants on the uterine wall varies, but it is usually about the sixth day after fertilization. By the end of the first week, a protective sac, known as the amniotic cavity, begins to form around the embryoblast.
EMBRYO AND FETUS.
Changes then begin to take place at a rapid rate. As each week passes, the embryo takes on more and more necessary and distinctive features, such as blood vessels in week 3, internal organs in week 5, and finger and thumb buds on the hands in week 7. Unfortunately, miscarriages are not uncommon in the early weeks of pregnancy. The mother's immune system (see Immune System) may react to cells from the embryo that it classifies as "foreign" and begin to attack those cells. The embryo may die and be expelled. The first three months of embryonic development are known as the first trimester, or the first three-month period of growth. At the end of the first trimester, the embryo is about 3 in. (7.5 cm) long and looks like a tiny version of an adult human. Thereafter, the growing organism is no longer an embryo, but a fetus. Fetal development continues through the second and third trimesters until the baby is ready for birth at the end of ninth months.
Preparing for Birth
At the end of the gestation period, the mother's uterus begins to contract rhythmically, a process called labor. This is accompanied by the release of hormones, most notably oxytocin. From the time of fertilization, quantities of the hormone progesterone, which keeps the uterus from contracting, are high; but during the last weeks of gestation, maternal progesterone levels begin to drop, while levels of the female hormone estrogen rise. When progesterone levels drop to very low levels and estrogen levels are highest, the uterus begins to contract.
Meanwhile, as birth approaches, the brain's pituitary gland releases oxytocin, a hormone that stimulates uterine contractions and controls the production of milk in the mammary glands (a process called lactation). Synthetic oxytocin sometimes is given to women to induce labor. Scientists believe that the pressure of the fetus's head against the cervix, the opening of the uterus, ultimately initiates the secretion of oxytocin. As the fetus's head presses against the cervix, the uterus stretches and relays a message along nerves to the pituitary gland, which responds by releasing oxytocin. The more the uterus stretches, the more oxytocin is released.
LABOR AND DELIVERY.
Rhythmic contractions dilate the cervix, causing the fetus to move down the birth canal and to be expelled together with the placenta, which has supplied the developing fetus with nutrients from the mother during the gestation period. Before delivery, the placenta separates from the wall of the uterus. Since the placenta contains many blood vessels, its separation from the wall of the uterus causes bleeding. This bleeding is normal, assuming that it is not excessive. After the placenta separates from the uterine wall, it moves into the birth canal and is expelled from the vagina. The uterus continues to contract even after the placenta is delivered, and it is thought that these contractions serve to control bleeding.
After the baby is born, the umbilical cord that has attached the fetus to the placenta is clamped. The clamping cuts off the circulation of the cord, which eventually stops pulsing owing to the interruption of its blood supply. The baby now must breathe air through its own lungs, whereas before it has been breathing, fishlike, in the warm, wet environment of the mother's amniotic fluid. The process of labor described here in a very cursory fashion (it is actually much more complicated) can take from less than one hour to 48 hours, but typically the entire birth process takes about 16 hours.
Changing Views on Childbirth
Before modern times, the realm of childbirth was a world exclusive to women, and few men ever entered the birth chamber. It was a place of excruciating pain and serious danger to the mother giving birth, so filled with blood and screaming that few men would have dared enter even if they had wanted to do so. Women had to give birth without anesthesia and any number of other amenities of modern medical care, including sophisticated diagnostic techniques and equipment, such as ultrasound, as well as antiseptic environments and surgical techniques, such as cesarean section.
In those days, birthing assistance was the work of midwives, women who lacked formal schooling in medicine (which was unavailable to most women in any case) but made up in experience for what they lacked in education. By about 1500, however, as medicine began to progress after many centuries of stagnation, male doctors increasingly forced midwives out of a job. In 1540 the European Guild of Surgeons declared that "no carpenter, smith, weaver, or woman shall practice surgery." A major turning point in the male takeover of birthing assistance duties came with the invention of the forceps, tong-like instruments that could be used for extracting a baby during difficult births. The inventor was the English obstetrician (a physician concerned with childbirth) Peter Chamberlen the Elder (1560-1631), and he and his descendants for a century closely guarded the design of the brilliant invention. Even the mothers on whom it was used never saw the instrument, and midwives were prohibited from using forceps to assist during childbirth.
OBSTETRICIANS TAKE OVER.
By the eighteenth century, however, Chamberlen's descendants had released their exclusive claim over the forceps, and use of the instrument spread to other medical professionals. This gave male obstetricians a great technological advantage over female midwives and further ensured the separation of the midwives from the medical profession. By 1750 numerous physicians and surgeons had gained the status of "man-mid-wives," and the growth of university courses on obstetrics established it as a distinct medical specialty. By the latter part of the 1700s, most women of the upper classes had come to rely on professionally trained doctors rather than midwives, yet in America, where doctors were scarcer than in Europe, the profession of midwife continued to flourish into the 1800s. Still, by the early twentieth century, childbirth had moved out of the home and into the hospital, and at mid-century it had become a completely medical process, attended by physicians and managed with medical equipment and procedures, such as fetal monitors, anesthesia, and surgical interventions.
THE REACTION IN THE LATE TWENTIETH CENTURY.
Many women of the late twentieth century found themselves dissatisfied with this clinical approach to childbirth. Some believed that the medical establishment had taken control of a natural biological process, and women who wanted more command over labor and delivery helped popularize new ideas on childbirth that sought to reduce or eliminate medical interventions. Today, some women choose to deliver with the help of a nurse-midwife, who, like her premodern counterparts, is trained to deliver babies but is not a doctor. There are women who even choose home birth, attended by a doctor or midwife or sometimes both. There are even brave souls who, in the face of increasing concern about the effect of anesthesia on the fetus, refuse artificial means of controlling pain and instead rely on breathing and relaxation techniques. For the first time in many years, the screams of women giving birth "naturally" once again filled the halls of hospital maternity wards and home birthing rooms.
The last few paragraphs represent an extreme reaction—a view not shared by many women, who have been more than happy to avail themselves of the benefits of childbirth in the modern world. Such benefits include an epidural, a type of anesthetic procedure that serves to alleviate the pain of parturition, or childbirth, while making it possible for the mother to remain conscious. Still, even for women who have no interest in giving birth at home or without the aid of drugs, much has changed in the world of childbirth. Women may choose a happy medium between the medical establishment and more traditional methods, for instance, by opting to consult with an obstetrician and a midwife.
Today, many obstetricians are women. This has had an incalculable effect on making childbirth psychologically easier for many women: though some are happy to retain a male obstetrician, many others find themselves much more comfortable being cared for by a physician who, in all likelihood, has given birth herself. The increasingly important role of the female obstetrician, along with other factors, serves to symbolize the fact that the world has progressed beyond the old false dilemma between medical care from a male or a female, between medicine and nature, between hospital and home.
A HOSPITAL AS HOME.
Hospital rooms, in fact, are starting to resemble rooms at home. Everywhere one looks in the modern maternity environment, there is evidence that much has changed, not only from the very old days, when male doctors were not involved in childbirth at all, but also from the more recent past, when males took over the process entirely. In a brilliant innovation, many hospitals have created a situation in which the woman gives birth in her own hospital room, which is outfitted with couches, cabinets, curtains, and rocking chairs to make it look like a home rather than a hospital. To emphasize the smooth transition between home life and the delivery room, fathers, once banished from the labor and delivery chambers, now are welcomed as partners in the birth process.
A father may even cut the umbilical cord, and he is certainly likely to be in the delivery room with a video camera, recording the event for posterity—yet another change from the past. Fathers are not the only ones filming in the delivery room. Today, cable television networks, such as the Learning Channel, provide programming that offers a frank view of the delivery process, complete with candid footage that sometimes can be as dramatic as it is revealing. The maternity ward, once a closed place, has increasingly become an open book.
Saving and Improving Lives
Many a mother and father alike can breathe a prayer (or at least a sigh) of thanks for all the innovations that today make birth much safer than it once was. Among them are a variety of techniques for embryo and fetal diagnosis, which help make parents aware of possible problems in the growing embryo. Ultrasound diagnosis, a technique similar to that applied on submarines for locating underwater structures, uses high-pitched sounds that cannot be heard by the human ear. These sounds are bounced off the embryo, and the echoes received are used to identify embryonic size.
By the eighteenth week of pregnancy, ultrasound technology can detect many structural abnormalities, such as spina bifida (various defects of the spine), hydrocephaly (water on the brain), anencephaly (no brain), heart and kidney defects, and harelip (in which the upper lip is divided into two or more parts). On a less dire and much more pleasant note, it can also give future parents an opportunity to gain their first glimpse of their child, and an experienced ultra-sound technician usually can tell them the baby's sex if they choose to learn it before the birth.
Chorionic villi sampling is the most sophisticated modern technique used to assess possible inherited genetic defects. This test typically is performed between the sixth and eighth week of embryonic development. During the test, a narrow tube is passed through the vagina or the abdomen, and a sample of the chorionic villi (small hairlike projections on the covering of the embryonic sac) is removed while the physician views the baby via ultrasound.
Chorionic villi are rich in both embryonic and maternal blood cells. By studying them, genetic counselors can determine whether the baby will have any of several defects, including Down syndrome (characterized by mental retardation, short stature, and a broadened face), cystic fibrosis (which affects the digestive and respiratory systems), and the blood diseases hemophilia, sickle cell anemia, and thalassemia. (Several of these disorders are discussed in different essays throughout this book; for instance, Down syndrome is examined in Mutation.) As with ultrasound, it also can show the baby's gender.
Another important form of prenatal (before the birth of the child) testing is amniocentesis, performed around week 16, in which amniotic fluid is drawn from the uterus by means of a needle inserted through the abdomen. Amniocentesis, too, can reveal the sex of the child, as well as a host of genetic disorders such as Tay-Sachs disease, cystic fibrosis, and Down syndrome. However, amniocentesis involves the risk of fetal loss as a result of disruption of the placenta. Chorionic villi sampling is even more risky, with an even higher possibility of fetal loss than amniocentesis, probably because it is conducted at an earlier stage.
In alpha-fetoprotein screening, which takes place somewhere between the 16th and 18th weeks, proteins from the amniotic sac and the fetal liver are taken as a means of screening for specific defects. Because of uncertainties involved in interpretation of the results, alpha-fetoprotein screening is not a common procedure.
Another extremely important technique that has saved the life of many babies and mothers is cesarean section. The normal position for a baby in delivery is head first; when a baby is in the breech position, with its bottom first, it poses grave dangers to both the mother and the child. Not only could the baby fail to emerge in time to begin breathing normally, thus running the risk of brain damage, but it also can become stuck, endangering the life of the mother. Today these dangers are overcome by such techniques as turning the baby and by cesarean section, an operation in which the baby is removed via surgery from the mother's abdomen. Cesarean sections may also be performed due to other complications, including fetal and/or maternal distress.
The term cesarean refers to the Roman emperor Julius Caesar (102-44 b.c.), who supposedly was delivered in this fashion. But the story of Caesar's birth is undoubtedly a legend: until the early modern era, cesarean sections were performed only to save a living baby after the mother had died in childbirth. The reason is that cesareans were likely to be fatal to the mother. Only in the late nineteenth century, by which time doctors had come to understand the importance of providing an antiseptic or germ-free environment, did cesarean sections become practical. Today the C-section, as it is called, has become a routine procedure—one that has saved literally hundreds of thousands, perhaps millions, of lives.
WHERE TO LEARN MORE
Assisted Reproduction Foundation (Web site). <http://www.reproduction.org/>.
Bainbridge, David. Making Babies: The Science of Pregnancy. Cambridge, MA: Harvard University Press, 2001.
Facts About Multiples (Web site). <http://mypage.direct.ca/c/csamson/multiples.html>.
Midwifery, Pregnancy, Birth and Breastfeeding (Web site). <http://www.moonlily.com/obc/>.
Pence, Gregory E. Who's Afraid of Human Cloning? Lanham, MD: Rowman and Littlefield, 1998.
Pregnancy and Birth (Web site). <http://pregnancy.about.com/mbody.htm>.
Pregnancy and Reproduction Topics. Medline/National Library of Medicine, National Institutes of Health (Web site). <http://www.nlm.nih.gov/medlineplus/pregnancyandreproduction.html>.
Rudy, Kathy. Beyond Pro-Life and Pro-Choice: Moral Diversity in the Abortion Debate. Boston: Beacon Press, 1996.
Vaughan, Christopher C. How Life Begins: The Science of Life in the Womb. New York: Times Books, 1996.
The stage of animal development in the uterus before the point at which the animal is considered a fetus. In humans this is equivalent to the first three months.
A set of trumpet-like tubes that carries a fertilized egg from the ovary to the uterus.
The process of cellular fusion that takes place in sexual reproduction. The nucleus of a male reproductive cell, or gamete, fuses with the nucleus of a female gamete to produce a zygote.
An unborn or unhatched vertebrate that has taken on the shape typical of its kind. An unborn human usually is called a fetus during the period from three months after fertilization to the time of birth.
The time between fertilization and birth, during which the unborn offspring develops in the uterus.
Molecules produced by living cells, which send signals to spots remote from their point of origin and induce specific effects on the activities of other cells.
Female reproductive organ that contains the eggs.
A term for an animal that gives birth to eggs that must develop before hatching. Compare with viviparous.
A term for an animal that produces eggs but retains them inside the body until hatching occurs, so that "live" offspring are born. Compare with oviparous and viviparous.
An egg cell.
A reproductive organ, found in most female mammals, in which an embryo and, later, a fetus grows and develops.
A passage from the uterus to the outside of the body.
A term for an animal that gives birth to live offspring. Compare with oviparous.
"Pregnancy and Birth." Science of Everyday Things. 2002. Encyclopedia.com. (May 22, 2013). http://www.encyclopedia.com/doc/1G2-3408600139.html
"Pregnancy and Birth." Science of Everyday Things. 2002. Retrieved May 22, 2013 from Encyclopedia.com: http://www.encyclopedia.com/doc/1G2-3408600139.html
Pregnancy and Birth
Pregnancy and Birth
A woman's decision to begin a pregnancy carries with it the acceptance of the lifelong responsibility to be a parent. Ideally, effective parenting begins even before the moment of conception, when the woman confirms her desire to have a child and is physically and mentally prepared for the challenges of pregnancy, birth, and parenting.
Pregnancy and birth are not isolated from the woman's surroundings and circumstances. The woman's family, community, and culture typically influence her decisions and behaviors. Diverse beliefs, taboos, expected behaviors, and cultural rituals surrounding the childbearing experience are handed down from generation to generation. A common cultural expectation is that children will be conceived when a woman is in a committed sexual relationship. Pregnancy out of wedlock is sometimes frowned upon, and men and, especially, women can be ostracized for their sexual behavior. Regions of a single country also can have an influence. For example, pregnancy and birth in an urban region often involve the use of high technology and delivery in a large medical center hospital, whereas pregnancy and birth in a rural region may involve no technology and delivery at home.
In many cultures, procreation is the primary reason for marriage. Motherhood may be considered the woman's most socially powerful role, and pregnant women have elevated status. Enormous pressure may be exerted on newly married couples to have a family as soon as possible. When pregnancy does not occur within a certain time period, the marital contract may be dissolved, permitting the man to take another wife who will give him children, preferably sons.
The physiological aspects of pregnancy are universal. Conception occurs when a sperm from a male fertilizes an egg from a woman. Fertilization typically results from sexual intercourse between a woman and a man, but it also may be the result of such technological alternatives as in vitro fertilization or artificial insemination. The product of conception is referred to as an ovum for the first fourteen days. During the next six weeks, it is referred to as an embryo. During the remainder of the pregnancy, the embryo of conception is called a fetus.
The ovum implants in the wall of the woman's uterus (womb) about seven days after fertilization. Following implantation, the ovum grows through cell division, and a separate structure—called the placenta—develops. The blood vessels of the placenta serve as a link between the woman and the developing baby, bringing oxygen and nourishment to the baby and removing its carbon dioxide and waste products.
Physical and Psychological Changes of Pregnancy
A full-term pregnancy lasts approximately forty weeks, or nine calendar months, and is divided into three phases, called trimesters, of three months each. During each trimester, the pregnant woman experiences various physical and psychological changes.
As the baby grows, the uterus enlarges, which produces an obvious change in the shape and appearance of the woman's body. Uterine enlargement is responsible for some of the physical and psychological changes that develop during the woman's pregnancy. High levels of two hormones that are present during pregnancy—estrogen and progesterone—trigger other physical and psychological changes.
During the first trimester, the woman may have morning sickness, which refers to persistent nausea or vomiting during the morning hours. Sometimes, though, the nausea can occur throughout the day or only in the evening. Other common changes during the first trimester are tender breasts and nipples, fatigue, and a desire for more sleep than usual, as well as frequent urination. Headaches and sensitivity to odors also may occur. In addition, the woman may notice that the skin surrounding her nipples has become darker and that a thin line of darker skin has appeared on her abdomen. During the second trimester, many of the physical changes disappear. Toward the end of the fifth month of pregnancy, the woman first feels the fetus move, an event that is called quickening. During the third trimester, the woman may have frequent backaches and may feel clumsy or awkward due to the change in her posture caused by the enlarging uterus. Other third-trimester physical changes include shortness of breath, heartburn or indigestion, more frequent urination, hemorrhoids, leg cramps, swollen ankles, and varicose veins. Shortness of breath is, however, frequently relieved about two to three weeks before birth, when lightening occurs, that is, when the uterus moves downward from the abdominal cavity into the pelvic cavity.
Psychological changes and associated behaviors are triggered not only by uterine enlargement and hormone levels, but also by the woman's culture. Studies of Western women indicate that during the first trimester, common feelings include excitement about the pregnancy or anger that an unplanned pregnancy has occurred. Feelings of ambivalence about a planned pregnancy are also common. On the one hand, the woman feels that she has achieved a much-desired goal, whereas on the other hand, she feels overwhelmed by the thought of caring for another human being. The woman also may feel worried or anxious about how she will cope with the birth and the care of a baby. The second trimester is frequently characterized as a time of psychological well-being. As the pregnancy progresses, the woman may have both positive and negative feelings about the changes in the size and shape of her body. The psychological changes of the third trimester may include a return of anxiety about the birth; concerns about changes in relationships with a partner, family, and friends; and financial worries. At the same time, the woman may feel excited about the forthcoming birth of her baby and the start of a new phase in her life.
Throughout pregnancy, dietary practices frequently are influenced by culture and folk beliefs. Foods and herbs may be used in rituals to ward off evil spirits. Pregnant women may be encouraged to eat certain foods, foods of a certain temperature, or foods of certain colors, and may be discouraged from eating other foods. Some foods are thought to be shocking to the woman's body or to cause a rash or other problem in the infant. Other foods are thought to influence the position in which the baby is born. In some cultures, the amount of food eaten is prescribed in the belief that less food will produce a smaller infant and, therefore, an easier birth. Food cravings may occur, especially during the second trimester, and then continue throughout the pregnancy.
The Woman's Partner
Although the majority of women throughout the world become pregnant through sexual intercourse with a male partner, some women have female partners, and some other women choose to be single parents. The available literature focuses primarily on reactions of the woman's male partner to her pregnancy.
The male partner also may experience physical and psychological changes during the pregnancy. He may experience the same ambivalence as the woman once the pregnancy is confirmed. On the one hand, the male partner feels very pleased that he is capable of procreation, whereas on the other, he feels overwhelmed by the thought of his responsibility for his child.
Many of the physical and psychological changes experienced by the male partner, which are referred to as the couvade syndrome, are anexpression of rituals associated with various cultures. Physical changes that appear throughout the pregnancy include indigestion, nausea and/or vomiting, bloating, changes in appetite, food cravings, increased urination, constipation, diarrhea, hemorrhoids, abdominal pain, backache, headache, toothache, difficult breathing, sensitivity to odors, skin rashes, itching, fatigue, leg cramps, unintentional weight gain, and even fainting spells. Psychological changes include changes in the man's feelings about his body, and such mood changes as irritability, restlessness, insomnia, nervousness, inability to concentrate, anxiety, depression, or conversely, an enhanced sense of well-being.
Interestingly, studies of men in Western cultures have shown that the presence or absence of a physiological or psychological change in the man is directly related to the presence or absence of that change in his pregnant partner. That is, if the pregnant woman experiences a particular physical or psychological change, her partner most likely will also experience that change. In contrast, if the pregnant woman does not experience a particular change, her partner most likely will also not experience that change.
Studies also have shown that men who are members of certain cultures, have blue collar jobs, have limited financial resources, had health problems before the pregnancy, and who feel very involved in the pregnancy may be especially susceptible to the development of the couvade syndrome. In contrast, men who do not develop the couvade syndrome may feel hostility about the pregnancy or, conversely, may feel a special empathy for the pregnant woman.
Several theories have been proposed to explain why the couvade syndrome develops. One theory proposes that the syndrome is a result of the man's unconscious envy of the woman's ability to create a child. Another theory proposes that the couvade syndrome is a result of the man's ambivalence about the pregnancy. Still another theory proposes that the couvade syndrome is a result of the man's identification with his pregnant partner. Research has not, however, supported any of these theories.
Developmental Tasks of Pregnancy
Pregnancy and the birth of a woman's first child mark her entry to true adulthood in many cultures. As pregnancy progresses, the woman faces the challenge of two developmental tasks. One developmental task is to accept the fetus as part of herself, yet as a separate being that is a product of conception. The woman achieves this task when she accepts her pregnancy, begins to think of herself as a mother, and prepares for childbirth. Another task for the woman is to change her child-mother relationship with her own mother to a peer, or adult, relationship. The woman will achieve this task more readily when a partner or friend is willing to provide the psychological support previously provided by her mother, and when the mother is ready to accept her daughter as an autonomous adult and accept herself as a grandparent.
Additional Developmental Tasks of Women in Partner Relationships
Pregnant women who have partners must face three other developmental tasks. One developmental task for the woman and her partner is the commitment to make each other and the coming child a priority in their lives. That task may involve adjustments in their usual social life with family members and friends, as well as adjustments in the family budget to provide for another family member. Another developmental task is the division of household responsibilities and responsibilities related to work. The pregnant woman may, for example, need help with household activities, such as heavy cleaning and care of pets. Furthermore, women and partners who both have careers may decide that one of them will take an extended leave from work after the baby is born. A third developmental task is the formation of a relationship that is emotionally and sexually satisfying to both the woman and her partner and that is characterized by open, honest communication.
Birth is the end of the pregnancy. It encompasses two major phases, referred to as labor and delivery. Labor typically begins with mild contractions of the uterus that occur five to thirty minutes apart. Each contraction lasts approximately thirty to forty seconds. As labor progresses, the contractions become stronger, occur more frequently, and last up to one minute. Throughout labor, the cervix (the opening of the uterus to the vagina, or birth canal) dilates progressively and the baby moves downward into the birth canal. Delivery occurs when the baby is born by being expelled from the birth canal or when a cesarean section is performed. Although the cesarean section rate varies from country to country, an increase in the cesarean method of birth is evident in both developed and developing countries. Cesarean birth requires a cut to be made through the abdominal wall and into the uterus. The woman receives medication so that she does not feel the cut. The physician then removes the baby and the placenta. When the baby is born through the birth canal, the placenta detaches from the uterine wall and is expelled through the birth canal. In some cultures, the placenta is considered sacred and is given a ceremonial burial at the family home. For example, some Maori people of New Zealand bury the placenta because they regard it as a twin who gave up life so the other twin, the live baby, could live.
In some cultures, pregnancy is viewed as a gift from God, and reliance on the spiritual aspects and sacredness of birth for a positive outcome is common. Throughout labor, the woman experiences sensations ranging from mild discomfort to intense pain. Cultural norms and expectations vary, such as acceptable vocalizations of pain, who may attend the birth and/or provide comfort and support, and the mother's birthing position. The belief that to give birth one must endure some pain is universal. Cultural norms about expressions of that pain vary from silence to frequent crying out. Herbal remedies; massage; relaxation and breathing exercises; medications administered by a physician, midwife, or nurse; and various rituals typically are employed to help alleviate the pain of labor and birth.
In many cultures, female members of the woman's extended family, especially mothers and mothers-in-law, provide comfort and support, with a lay midwife present for the birth. In other cultures, a nurse midwife is present for the labor and birth. In still other cultures, a registered nurse may be present for the labor and birth, and a physician delivers the infant. The woman's position varies from standing and/or walking to reclining in bed during labor, and from squatting to reclining in bed for the baby's birth.
The setting for birth also varies across cultures. In many cultures, the woman's home or the home of a relative is regarded as the most psychologically safe and comfortable birth environment. In other cultures, a hospital is viewed as most appropriate. In still other cultures, women and their partners may plan to have their baby at home but are ready to go to a hospital if a difficulty is encountered.
The role of a male partner during birth varies among cultures. In many cultures, norms about modesty may prohibit a male partner or other men from being with the woman during labor and delivery. In other cultures, the male partner is expected to be present, if only to observe the woman's suffering and be more willing to participate in family planning. In still other cultures, the male partner is regarded as a provider of much support and comfort to the laboring woman.
Women and their partners or such other support persons as family members or friends who plan to be together for the labor and birth can learn the proper relaxation and breathing exercises in childbirth preparation classes taught by trained childbirth educators. These classes also help the woman and support person to understand what happens during labor and delivery and to learn how the woman's support person can be present at the birth to coach her throughout labor and delivery.
Pregnancy and birth can be a very special time in the life of a woman. The nine months of pregnancy, as well as labor and delivery, are filled with many physical and psychological changes, as well as changes in lifestyle. Each change poses a challenge that can be met successfully when the woman shares her feelings and experiences with a partner or other supportive person and with her physician, midwife, nurse, and childbirth educator. The importance of health care throughout pregnancy is emphasized, because proper health care increases the likelihood of a healthy pregnancy, a healthy baby, and satisfied parents. Many references, particularly the Human Relations Area Files, describe cultural variations in beliefs about pregnancy and birth and associated behaviors.
callister, l. c. (1995). "cultural meanings of childbirth." journal of obstetric, gynecologic and neonatal nursing 24:327–331.
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chalmers, b. (1997). "childbirth in eastern europe." midwifery 13:2–8.
davis-floyd, r. (1992). birth as an american rite of passage. berkeley: university of california press.
depacheo, m. r., and hutti, m. h. (1998). "cultural beliefs and health care practices of childbearing puerto rican american women and mexican american women." mother baby journal 3(1):14–22.
desevo, m. (1997). "keeping the faith: jewish traditions in pregnancy and childbirth." awhonn lifelines 1(4):46–49.
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la torra, g. (1996). "cultural beliefs about pregnancy and birth." international journal of childbirth education 11(2):36–38.
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nichols, f. (1996). "the meaning of the childbirth experience: a review of the literature." journal of perinatal education 5(4):71–77.
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"Pregnancy and Birth." International Encyclopedia of Marriage and Family. 2003. Encyclopedia.com. (May 22, 2013). http://www.encyclopedia.com/doc/1G2-3406900336.html
"Pregnancy and Birth." International Encyclopedia of Marriage and Family. 2003. Retrieved May 22, 2013 from Encyclopedia.com: http://www.encyclopedia.com/doc/1G2-3406900336.html
Pregnancy is the period from conception to birth. After the egg is fertilized by a sperm and then implanted in the lining of the uterus, it develops into the placenta and embryo, and later into a fetus. Pregnancy usually lasts 40 weeks, beginning from the first day of the woman's last menstrual period. The condition is divided into three trimesters, each lasting three months.
Pregnancy is a state in which a woman carries a fertilized egg inside her body.
At the end of the first month, the embryo is about 1/3 in long (.85 cm), and its head, trunk, and the beginnings of arms and legs have started to develop. The embryo gets nutrients and eliminates waste through the umbilical cord and placenta. By the end of the first month, the liver and digestive system begin to develop, and the heart starts to beat.
In this month, the heart starts to pump and the nervous system (including the brain and spinal cord) begins to develop. The 1 in (2.5 cm) long fetus has a complete cartilage skeleton, which is replaced by bone cells by month's end. Arms, legs, and all of the major organs begin to appear. Facial features begin to form.
By now, the fetus has grown to 4 in (10 cm) and weighs a little more than an ounce (28 g). Now the major
blood vessels and the roof of the mouth are almost completed. The face starts to take on a more recognizably human appearance. Fingers and toes appear. All the major organs are now beginning to form; the kidneys are now functional, and the four chambers of the heart are complete.
The fetus begins to kick and swallow, although most women still can't feel the baby move at this point. Now 4 oz (112 g) in weight, the fetus can hear and urinate, and has established sleep-wake cycles. All organs are now fully formed, although they will continue to grow for the next five months. The fetus has skin, eyebrows, and hair.
Now weighing up to 1 lb (454 g) and measuring 8–12 in (20–30 cm), the fetus experiences rapid growth as its internal organs continue to grow. At this point, the mother may feel her baby move, and she can hear the heartbeat with a stethoscope.
Even though its lungs are not fully developed, a fetus born during this month can survive with intensive care. Weighing 1–1.5 lbs (454–681 g), the fetus is red, wrinkly, and covered with fine hair all over its body. The fetus will grow very fast during this month as its organs continue to develop.
There is a better chance that a fetus born during this month will survive. The fetus continues to grow rapidly and may weigh as much as 3 lbs (1.3 kg) by now. Now the fetus can suck its thumb and look around its watery environment with open eyes.
Growth continues but slows down as the baby begins to take up most of the room inside the uterus. Now weighing between 4–5 lbs (1.8–2.3 kg) and measuring 16–18 in (40–45 cm) long, the fetus may at this time prepare for delivery next month by moving into the head-down position.
Adding 0.5 lb (227 g) a week as the due date approaches, the fetus drops lower into the mother's abdomen and prepares for the onset of labor, which may begin any time between the 37th and 42nd week of gestation. Most healthy babies will weigh 6–9 lbs (2.7–4 kg) at birth, and will be about 20 in (50 cm) long.
Causes & symptoms
Pregnancy is caused by a sperm fertilizing an egg. The first sign of pregnancy is usually a missed menstrual period, although some women bleed in the beginning. A woman's breasts swell and may become tender as the mammary glands prepare for eventual breastfeeding. Nipples begin to enlarge and the veins over the surface of the breasts become more noticeable.
Nausea and vomiting are very common symptoms that generally occur during the first three months of pregnancy. Since these symptoms are usually worse in the morning, this condition is known as morning sickness . Many women also feel extremely tired during the early weeks. Frequent urination is common, and there may be a creamy white discharge from the vagina. Some women crave certain foods, and an extreme sensitivity to smell may worsen the nausea. Weight begins to increase.
In the second trimester (13–28 weeks) a woman begins to look noticeably pregnant and the enlarged uterus is easy to feel. The nipples get bigger and darker, the skin of Caucasians may darken, and some women may feel flushed and warm. Appetite may increase. By the 22nd week, most women have felt the baby move. During the second trimester, nausea and vomiting often fade away, and the pregnant woman often feels much better and more energetic. Heart rate increases as does the volume of blood in the body.
By the third trimester (29–40 weeks), many women begin to experience a range of common symptoms. Stretch marks (striae) may develop on the abdomen, breasts and thighs, and a dark line may appear from the navel to pubic hair. A thin fluid may be expressed from the nipples. Many women feel hot, sweat easily, and often find it hard to get comfortable. Kicks from an active baby may cause sharp pains, and lower backaches are common. More rest is needed as the woman copes with the added stress of extra weight. Braxton Hicks contractions may get stronger.
At about the 36th week in a first pregnancy (later in repeat pregnancies), the baby's head drops down low into the pelvis. This shift may relieve pressure on the upper abdomen and the lungs, allowing a woman to breathe more easily. The fetus' new position, however, places more pressure on the bladder.
The average woman gains 28 lbs (12.7 kg) during pregnancy, 70% of it during the last 20 weeks. An average healthy full-term baby at birth weighs 7.5 lbs (3.4 kg), and the placenta and fluid together weigh another 3 lbs (1.3 kg). The remaining weight that a woman gains during pregnancy is mostly due to water retention and fat stores.
In addition to the typical symptoms of pregnancy, some women experience other problems that may be annoying but usually disappear after delivery. Constipation may develop as a result of food passing more slowly through the intestine. Hemorrhoids and heartburn are fairly common during late pregnancy. Gums may become more sensitive and bleed more easily; eyes may dry out, making contact lenses feel painful. Pica (a craving to eat substances other than food) may occur. Swollen ankles and varicose veins may be a problem in the second half of pregnancy, and chloasma (light brown spots) may appear on the face.
While the preceding symptoms are considered normal, there are some symptoms that may be signs of a more dangerous underlying problem. A pregnant woman experiencing any of the following should contact her doctor immediately:
Many women first discover they are pregnant after a positive home pregnancy test. Pregnancy urine tests check for the presence of human chorionic gonadotropin (hCG), which is produced by a placenta. Home tests can detect pregnancy on the day of the missed menstrual period.
Home pregnancy tests are more than 97% accurate if the result is positive, and about 80% accurate if the result is negative. If the result is negative and there is no menstrual period within another week, the pregnancy test should be repeated. While home pregnancy tests are very accurate, they are less accurate than a pregnancy test evaluated by a laboratory. For this reason, a woman may want to consider having a second pregnancy test conducted at her doctor's office to be sure of the accuracy of the result.
Blood tests to determine pregnancy are usually used only when a very early diagnosis of pregnancy is needed. This more expensive test, which also looks for hCG, can produce a result within 9–12 days after conception.
Once pregnancy has been confirmed, there are a range of screening tests that can be done to screen for birth defects, which affect about 3% of unborn children. Two tests are recommended for all pregnant women: alpha-fetoprotein (AFP) and the triple marker test.
Other tests are recommended for women at higher risk for having a child with a birth defect. These groups include women over age 35 who had another child or a close relative with a birth defect, or who have been exposed to certain drugs or high levels of radiation. Women with any of these risk factors may want to consider amniocentesis, chorionic villus sampling (CVS) or ultrasound.
Other prenatal tests
There are a range of other prenatal tests that are routinely performed, including:
Alternative medicine offers a variety of treatments for conditions ranging from morning sickness to stretch marks. Before starting any treatment, a pregnant woman should consult with her doctor or practitioner.
Prenatal care is vitally important for the health of the unborn baby. A pregnant woman should eat a balanced, nutritious diet of frequent small meals. Many physicians prescribe pregnancy vitamins, including folic acid and iron supplementation during pregnancy.
Numerous herbs are believed to remedy a range of conditions experienced by pregnant women. Many remedies can be taken as herbal teas, and packaged tea bags are sold at health food stores. The following herbs are recommended for pregnant women:
HERBS TO AVOID. Some herbs can cause complications and should not be taken during pregnancy. Uterine contractions can be caused by angelica , lovage, mistletoe, mugwort , tansy, wild ginger, and wormwood . Other herbs to be avoided include cinchona, eucalyptus oil, juniper , ma huang (ephedra ), male fern, pennyroyal , poke root, rue, shepherd's purse, and yarrow .
Aromatherapy involves the use of essential oils as remedies. The application of combined oils to the skin is said to counteract stretch marks. An aromatherapist can recommend specific oil combinations.
Chinese medicine and acupuncture
In addition to giving herbs for infertility problems, traditional Chinese medicine recommends herbal formulas for such problems associated with pregnancy as morning sickness, threatened miscarriage, and postpartum depression . One well-known formula, recommended to be taken three to six months before attempting conception, is called "The Rock on Tai Mountain Decoction." The formula is intended to build up both the woman's qi, or life energy, and her blood. In Chinese medicine it is thought that the mother's blood nourishes, the qi protects, and the qi in the kidneys holds the fetus.
Chinese practitioners use acupuncture to assist conception by clearing the stagnation of qi in the liver; to prevent miscarriage by conserving qi in the kidney; and to induce labor.
Traditional Chinese medicine recommends abstinence from sex during pregnancy in order to allow the placenta to develop normally and to prevent harm caused by sexual excess to the various organs and substances in the mother's body. Although the Chinese are not puritanical in the Western sense of that word, they believe that good health requires moderation in all things, including sex.
Although pregnant women should avoid saunas and hot tubs, other forms of hydrotherapy can provide relief. To ease nausea, a warm compress is placed between the chest and abdomen 30 minutes before eating. The compress is a cloth soaked in hot water and wrung out. A foot bath can soothe swollen feet.
Morning sickness can be treated by several homeopathic remedies. If a homeopathic remedy is a decimal potency, it is indicated by an "x" This indicates the number of times that one part of a remedy was diluted in nine parts of a diluent. Distilled water is the preferred diluent.
Ipecacuanha 30x is recommended if the woman feels worse lying down, has diarrhea , and is salivating heavily. If morning sickness is accompanied by queasiness about eating, Colchicum autumnale 6x is recommended. Nux vomica 6x is the remedy when a woman vomits in the morning, but her condition improves after eating. Phosphorus 6x is taken when a woman vomits after drinking water. For nausea only, Natrum phosporicum 6x may provide relief.
Each remedy is taken every 15 minutes until the feeling of nausea lessens. However, no more than four doses should be taken in one day unless specified by a homeopath.
Flower remedies are liquid concentrates made by soaking flowers in spring water. Also known as flower essences, 38 remedies were developed by homeopathic physician Edward Bach during the 1930s. Walnut, a Bach remedy for difficulty in adjusting to change, may be helpful to pregnant women. A 39th combination formula, the rescue remedy , is taken to relieve stress. A pregnant woman should, however, check with her doctor before beginning flower therapy. The essence, which contains alcohol, is taken in water and usually sipped.
Relaxation techniques can be used to cope with such conditions as stress or morning sickness. Helpful techniques include meditation , deep breathing, and listening to relaxation tapes. Another useful technique is guided imagery ; the person does some deep breathing and then visualizes a positive image or affirmation.
Massaging sore areas of the body during pregnancy can reduce aches and stress. Another form of bodywork is the Alexander technique , developed by actor Frederick Matthias Alexander during the 1800s. An Alexander technique practitioner can show a woman how to release muscle tension, with emphasis on the neck. The technique focuses on posture and movement. It is said to reduce stress and relieve pain in such areas as the back.
No medication (not even a nonprescription drug) should be taken except under medical supervision, since it could pass from the mother through the placenta to the developing baby. Some drugs have been proven harmful to a fetus, but no drug should be considered completely safe. Drugs taken during the first three months of a pregnancy may interfere with the normal formation of the baby's organs, leading to birth defects. Drugs taken later on in pregnancy may slow the baby's growth rate, or they may damage specific fetal tissue (such as the developing teeth).
To have the best chance of having a healthy baby, a pregnant woman should avoid:
Pregnancy is a natural condition that usually causes little discomfort provided the woman takes care of herself and gets adequate prenatal care. Childbirth education classes for the woman and her partner help prepare the couple for labor and delivery.
There are many ways to avoid pregnancy. A woman has a choice of many methods of contraception that will prevent pregnancy, including (in order of least to most effective):
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Carlson, Karen J., Stephanie A. Eisenstat, and Terra Ziporyn. The Harvard Guide to Women's Health. Cambridge, MA: Harvard University Press, 1996.
Gottlieb, Bill, ed. New Choices in Natural Healing. Emmaus, PA: Rodale Press, Inc., 1995.
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Healthy Mothers, Healthy Babies National Coalition. 409 12th St. Washington, DC 20024. (202) 638-5577.
Herb Research Foundation. 1007 Pearl St., Suite 200. Boulder, CO 80302. (303) 449-2265. http://www.herbs.org.
National Institute of Child Health and Human Development. 9000 Rockville Pike, Bldg. 31, Rm. 2A32. Bethesda, MD 20892. (301) 496-5133.
Swain, Liz. "Pregnancy." Gale Encyclopedia of Alternative Medicine. 2005. Encyclopedia.com. (May 22, 2013). http://www.encyclopedia.com/doc/1G2-3435100626.html
Swain, Liz. "Pregnancy." Gale Encyclopedia of Alternative Medicine. 2005. Retrieved May 22, 2013 from Encyclopedia.com: http://www.encyclopedia.com/doc/1G2-3435100626.html
Nutrition during the preconception period, as well as throughout a pregnancy, has a major impact on pregnancy outcome. Among prepregnancy considerations, the prepregnancy Body Mass Index (BMI), folic acid status, and socioeconomic status are the most important.
Prepregnancy BMI is an important factor in predicting pregnancy outcome, since both low prepregnancy and high prepregnancy BMI are associated with an increased risk for a negative pregnancy outcome.
Folic acid, a B vitamin, has been shown to prevent birth defects of the brain and spinal cord known as neural tube defects (NTDs). The most common NTDs are spina bifida and anencephaly. Folic acid is therefore needed
both in preconception and early pregnancy. Since studies indicate that most women get less than half the recommended amount of folic acid, the March of Dimes recommends women consider a supplement of 400 micrograms of folic acid preconceptually to prevent the incidence of neural tube defects. In addition, it is suggested women capable of becoming pregnant consume a diet high in folic acid. Good sources of folic acid include oranges, green leafy vegetables, and fortified bread and cereals.
There is also a direct correlation between ethnicity, age, marital status, and educational status with increased negative pregnancy outcomes, such as low birth weight.
Pregnancy Weight Gain
Pregnancy is divided into three trimesters, with each trimester lasting three months, or approximately thirteen weeks (a normal pregnancy lasts 40 weeks). Recommendations for weight gain during pregnancy are based on the Institute of Medicine (IOM) definitions of prepregnancy BMI range. The BMI is defined as weight in pounds, divided by height in inches, divided by height in inches, multiplied by 703 (or weight in kilograms, divided by height in centimeters, divided by height in centimeters, multiplied by ten-thousand). The majority of weight gain should occur in the second and third trimesters. Weight gain can vary greatly in normal pregnancies with normal birth outcomes. Few studies have included women in their first trimester, so the importance of first-trimester weight gain on pregnancy outcome is unclear. However, a slow and steady rate of weight gain is considered ideal. The current recommended weight gain for the BMI ranges are outlined in the accompanying figure.
Poor weight gain during pregnancy is associated with prematurity, low birth weight, and small for gestational age. Among normal-weight women, weight gain above the recommended level corresponds to maternal fat stores and is not of benefit to fetal growth. In other words, fat gain during pregnancy parallels gestational weight gain, and women with greater weight gain also gain more fat. In addition, an inverse relationship exists between pre-pregnancy BMI and weight gain during pregnancy: women with a low pre-pregnancy BMI tend to gain more weight than women with a high prepregnancy BMI. On average, overweight women gain less weight than their thinner counterparts, though it is not unusual for obese women to achieve normal birth outcomes with less than the recommended weight gain.
In adolescent pregnancies, there are no established BMI recommendations regarding prepregnancy weight and weight gain. Excess weight gain, however, has been associated with postpartum obesity in adolescents.
Pregnancy Nutrition Requirements
Traditionally, caloric requirements during pregnancy have been estimated to be around an additional 300 calories per day. However, this must be adjusted for physical activity and prepregnancy weight (see accompanying figure) for the recommended number of servings of food groups). To meet weight-gain recommendations, a woman with a low prepregnancy BMI and a high activity level would require more calories than a woman with a high prepregnancy BMI and a sedentary lifestyle . A variety of foods from all food groups is important, since foods within the same food group do not contain exactly the same amount of nutrients . If increased weight gain is recommended, an emphasis should be placed on high-calorie food group items that contain a higher fat and sugar content. When less weight gain is recommended, women should choose from the lower-calorie food group choices.
Recommendations regarding sugar intake for pregnant women depend on weight gain and maternal blood glucose levels. A high sugar intake would not be advisable for women gaining more than the recommended weight or for those women who are having difficulty controlling normal blood glucose levels, while a high sugar intake would be beneficial for women requiring increased weight gain. A high sugar intake for women who are experiencing excessive weight gain or having difficulty maintaining normal glucose levels could result in increased maternal risk for complications associated with too much weight gain, such as diabetes , hypertension , premature delivery, and a large for gestational age fetus.
Adequate fluid intake is important to maintain hemodynamics (blood circulation) and homeostasis (fluid and tissue balance) and to reduce the risk of urinary tract infections. All pregnant women are encouraged to consume at least 64 ounces of fluid daily. Women at risk of gaining too much weight should be cautioned to limit their intake of sweetened fluids, including juice, and to consume more water. Exercise is considered healthful for most pregnant women, who should be encouraged to continue to exercise at prepregnancy levels. However, women should be cautious about beginning any new exercise program during pregnancy, and, if medically advised, should avoid certain activities. Health care providers may recommend bed rest and limiting physical activity (such as work) when preterm labor is present or when weight gain is poor. Increased physical activity will control excess weight gain, in addition to the normal beneficial physical and emotional effects.
Vitamin and Mineral Requirements
Iron is the only recommended nutrient for which requirements cannot be reasonably met by diet alone during pregnancy. Thirty milligrams of ferrous iron is recommended, and iron should be taken on an empty stomach. When more than 30 mg of iron is given to treat anemia , it is suggested to also take approximately 15 mg of zinc and 2 mg of copper, since iron interferes with absorption and utilization of these materials.
According to some studies, caffeine decreases the availability of certain nutrients, such as calcium , zinc, and iron. Current recommendations, therefore, include limiting the consumption of caffeinated containing products.
Calcium supplementation may be suggested if the average daily intake of calcium is less than 600 mg. Calcium intake is of particular concern among pregnant women under the age of twenty-five, since bone mineral density is still increasing in these women. Calcium supplements, if recommended, should be taken with meals. Additionally, vitamin D may be necessary if sunlight exposure is minimal. For vegetarians, the current recommendations also include a daily supplement of 2 mg of Vitamin B12.
For women who don't ordinarily consume an adequate diet, or for those in high-risk categories (such as those carrying twins, heavy smokers, and drug abusers) a prenatal vitamin supplement is recommended, beginning in the second trimester. The supplement should contain the following: iron (30 mg); zinc (15 mg); copper (2 mg); calcium (250 mg); vitamin B6 (62 mg); folate (300 mg); vitamin C (50 mg); vitamin D (5 mg).
Special Nutrition Concerns
Food cravings during pregnancy are common and are not cause for concern, provided other nutrient needs are met and weight gain is in the target range. Pica—the ingestion of nonfood substances of nutritional value—is associated with anemia and can be a source of lead poisoning, bacterial infection, and dental problems. Pregnant women should be encouraged to avoid pica and discuss it with their medical provider.
Gestational diabetes is associated with high prepregnancy BMI and excess pregnancy weight gain. Infants of gestational-diabetic mothers are usually born large for gestational age (macrosomia) and are at higher risk for cesarean delivery and hypoglycemia postpartum.
Symptoms of toxemia of pregnancy, also known as preeclampsia, include swelling (edema ) and proteinuria (excess protein in the urine). The cause of toxemia has not been determined, but the risk is associated with first pregnancies, advanced maternal age, African-American ethnicity, and women with a past history of diabetes, hypertension, or kidney disease. In severe cases, delivery is frequently induced.
Tips for common pregnancy discomforts include avoidance of offending foods (and their odor) when nausea and heartburn occur. Many pregnant women find that spicy, fatty foods can increase problems with nausea and heartburn. Frequent, small, and blander meals are often better tolerated. Some women find eating dry crackers before rising from bed in the morning helpful for nausea. However, since nausea and vomiting usually subside by the end of the first trimester, they do not have a significant impact on the final weight gain in most pregnancies. Hyperemesis gravidarum, or intractable vomiting during pregnancy, can rapidly result in dehydration , so medical intervention is required.
When constipation is a concern, increased consumption of whole grains, fruits, and vegetables is advisable, as well as increased fluid intake and physical activity.
Breastfeeding is the recommended method of infant nutrition, with a few exceptions. It benefits both mother and infant by providing protective antibodies to human disease, and breastfed babies are generally healthier and have higher I.Q. levels than bottle-fed babies. The development of jaw alignment problems and allergies are also far less likely in breastfed babies, while mothers who breastfeed have less postpartum complications and are considered to be at lower risk for breast cancer .
In the United States, women with HIV infection should not breastfeed. This is not a contraindication in developing countries, however, as the benefits may outweigh the possibility of infection. Untreated tuberculosis is also a contraindication for breastfeeding, while hepatitis C is currently not a contraindication for breastfeeding.
The Women, Infants, and Children (WIC) Program
The WIC program was established in the 1970s as a supplemental food and nutrition-education program. Eligibility requirements include a household income of up to 185 percent of the federal poverty level, as well as nutrition-risk criteria. The WIC program goals include improving pregnancy outcomes by helping participants achieve recommended weight gain. Nutritional food choices and calorie levels based on recommended weight gain are emphasized. The program has been shown to significantly reduce a number of negative pregnancy outcomes, including low birth weight.
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The period from conception to birth. After the egg is fertilized by a sperm and then implanted in the lining of the uterus, it develops into the placenta and embryo, and later into a fetus. Pregnancy usually lasts 40 weeks, beginning from the first day of the woman's last menstrual period, and is divided into three trimesters, each lasting three months.
Pregnancy is a state in which a woman carries a fertilized egg inside her body. Due to technological advances, pregnancy is increasingly occurring among older women in the United States.
At the end of the first month, the embryo is about a third of an inch long, and its head and trunk-plus the beginnings of arms and legs-have started to develop. The embryo receives nutrients and eliminates waste through the umbilical cord and placenta. By the end of the first month, the liver and digestive system begin to develop, and the heart starts to beat.
In this month, the heart starts to pump and the nervous system (including the brain and spinal cord) begins to develop. The 1 in (2.5 cm) long fetus has a complete cartilage skeleton, which is replaced by bone cells by month's end. Arms, legs and all of the major organs begin to appear. Facial features begin to form.
By now, the fetus has grown to 4 in (10 cm) and weighs a little more than an ounce (28 g). Now the major blood vessels and the roof of the mouth are almost completed, as the face starts to take on a more recognizably human appearance. Fingers and toes appear. All the major organs are now beginning to form; the kidneys are now functional and the four chambers of the heart are complete.
The fetus begins to kick and swallow, although most women still can't feel the baby move at this point. Now 4 oz (112 g), the fetus can hear and urinate, and has established sleep-wake cycles. All organs are now fully formed, although they will continue to grow for the next five months. The fetus has skin, eyebrows, and hair.
Now weighing up to a 1 lb (454 g) and measuring 8-12 in (20-30 cm), the fetus experiences rapid growth as its internal organs continue to grow. At this point, the mother may feel her baby move, and she can hear the heartbeat with a stethoscope.
Even though its lungs are not fully developed, a fetus born during this month can survive with intensive care. Weighing 1-1.5 lbs (454-681 g), the fetus is red, wrinkly, and covered with fine hair all over its body. The fetus will grow very fast during this month as its organs continue to develop.
There is a better chance that a fetus born during this month will survive. The fetus continues to grow rapidly, and may weigh as much as 3 lb (1.3 kg) by now. Now the fetus can suck its thumb and look around its watery womb with open eyes.
Growth continues but slows down as the baby begins to take up most of the room inside the uterus. Now weighing 4-5 lbs (1.8-2.3 kg) and measuring 16-18 in (40-45 cm) long, the fetus may at this time prepare for delivery next month by moving into the head-down position.
Adding 0.5 lb (227 g) a week as the due date approaches, the fetus drops lower into the mother's abdomen and prepares for the onset of labor, which may begin any time between the 37th and 42nd week of gestation. Most healthy babies will weigh 6-9 lb (2.7-4 kg) at birth, and will be about 20 in. long.
Causes and symptoms
The first sign of pregnancy is usually a missed menstrual period, although some women bleed in the beginning. A woman's breasts swell and may become tender as the mammary glands prepare for eventual breastfeeding. Nipples begin to enlarge and the veins over the surface of the breasts become more noticeable.
Nausea and vomiting are very common symptoms and are usually worse in the morning and during the first trimester of pregnancy. They are usually caused by hormonal changes, in particular, increased levels of progesterone. Women may feel worse when their stomach is empty, so it is a good idea to eat several small meals throughout the day, and to keep things like crackers on hand to eat even before getting out of bed in the morning.
Many women also feel extremely tired during the early weeks. Frequent urination is common, and there may be a creamy white discharge from the vagina. Some women crave certain foods, and an extreme sensitivity to smell may worsen the nausea. Weight begins to increase.
In the second trimester (13-28 weeks) a woman begins to look noticeably pregnant and the enlarged uterus is easy to feel. The nipples get bigger and darker, skin may darken, and some women may feel flushed and warm. Appetite may increase. By the 22nd week, most women have felt the baby move. During the second trimester, nausea and vomiting often fade away, and the pregnant woman often feels much better and more energetic. Heart rate increases as does the volume of blood in the body.
By the third trimester (29-40 weeks), many women begin to experience a range of common symptoms. Stretch marks may develop on abdomen, breasts, and thighs, and a dark line may appear from the navel to pubic hair. A thin fluid may be expressed from the nipples. Many women feel hot, sweat easily and often find it hard to get comfortable. Kicks from an active baby may cause sharp pains, and lower backaches are common. More rest is needed as the woman copes with the added stress of extra weight. Braxton Hicks contractions may get stronger.
At about the 36th week in a first pregnancy (later in repeat pregnancies), the baby's head drops down low into the pelvis. This may relieve pressure on the upper abdomen and the lungs, allowing a woman to breathe more easily. However, the new position places more pressure on the bladder.
A healthy gain for most women is between 25 and 35 pounds. Women who are overweight should gain less; and women who are underweight should gain more. On average, pregnant women need an additional 300 calories a day. Generally, women will gain three to five pounds in the first three months, adding one to two pounds a week until the baby is born. An average, healthy full-term baby at birth weighs 7.5 lb (3.4 kg), and the placenta and fluid together weigh another 3.5 lb. The remaining weight that a woman gains during pregnancy is mostly due to water retention and fat stores. Her breasts, for instance, gain about 2 lb. in weight, and she gains another 4 lb due to the increased blood volume of pregnancy.
In addition to the typical, common symptoms of pregnancy, some women experience other problems that may be annoying, but which usually disappear after delivery. Constipation may develop as a result of food passing more slowly through the intestine. Hemorrhoids and heartburn are fairly common during late pregnancy. Gums may become more sensitive and bleed more easily; eyes may dry out, making contact lenses feel painful. Pica (a craving to eat substances other than food) may occur. Swollen ankles and varicose veins may be a problem in the second half of pregnancy, and chloasma may appear on the face.
Chloasma, also known as the "mask of pregnancy" or melasma, is caused by hormonal changes that result in blotches of pale brown skin appearing on the forehead, cheeks, and nose. These blotches may merge into one dark mask. It usually fades gradually after pregnancy, but it may become permanent or recur with subsequent pregnancies. Some women also find that the line running from the top to the bottom of their abdomen darkens. This is called the linea nigra.
While the above symptoms are all considered to be normal, there are some symptoms that could be a sign of a more dangerous underlying problem. A pregnant woman with any of the following signs should contact her doctor immediately:
Many women first discover they are pregnant after a positive home pregnancy test. Pregnancy urine tests check for the presence of human chorionic gonadotropin (hCG), which is produced by a placenta. The newest home tests can detect pregnancy on the day of the missed menstrual period.
Home pregnancy tests are more than 97% accurate if the result is positive, and about 80% accurate if the result is negative. If the result is negative and there is no menstrual period within another week, the pregnancy test should be repeated. While home pregnancy tests are very accurate, they are less accurate than a pregnancy test conducted at a lab. For this reason, women may want to consider having a second pregnancy test conducted at their doctor's office to be sure of the accuracy of the result.
Blood tests to determine pregnancy are usually used only when a very early diagnosis of pregnancy is needed. This more expensive test, which also looks for hCG, can produce a result within nine to 12 days after conception.
Once pregnancy has been confirmed, there are a range of screening tests that can be done to screen for birth defects, which affect about 3% of unborn children. Two tests are recommended for all pregnant women: alpha-fetoprotein (AFP) and the triple marker test.
Other tests are recommended for women at higher risk for having a child with a birth defect. This would include women over age 35, who had another child or a close relative with a birth defect, or who have been exposed to certain drugs or high levels of radiation. Women with any of these risk factors may want to consider amniocentesis, chorionic villus sampling (CVS) or ultrasound.
Other prenatal tests
There are a range of other prenatal tests that are routinely performed, including:
Prenatal care is vitally important for the health of the unborn baby. A pregnant woman should be sure to eat a balanced, nutritious diet of frequent, small meals. Women should begin taking 400 mcg of folic acid several months before becoming pregnant, as folic acid has been shown to reduce the risk of spinal cord defects, such as spina bifida.
No medication (not even a nonprescription drug) should be taken except under medical supervision, since it could pass from the mother through the placenta to the developing baby. Some drugs, called teratogens, have been proven harmful to a fetus, but no drug should be considered completely safe (especially during early pregnancy). Drugs taken during the first three months of a pregnancy may interfere with the normal formation of the baby's organs, leading to birth defects. Drugs taken later on in pregnancy may slow the baby's growth rate, or they may damage specific fetal tissue (such as the developing teeth), or cause preterm birth.
To have the best chance of having a healthy baby, a pregnant woman should avoid:
Women should begin following a healthy diet even before they become pregnant. This means cutting back on high-calorie, high-fat, high-sugar snacks, and increasing the amount of fruits, vegetables and whole grains in her diet. Once she becomes pregnant, she should make sure to get at least six to 11 servings of breads and other whole grains, three to five servings of vegetables, two to four servings of fruits, four to six servings of milk and milk products, three to four servings of meat and protein foods, and six to eight glasses of water. She should limit caffeine to no more than one soft drink or cup of coffee per day.
Pregnancy is a natural condition that usually causes little discomfort provided the woman takes care of herself and gets adequate prenatal care. Childbirth education classes for the woman and her partner help prepare the couple for labor and delivery.
Alpha-fetoprotein— A substance produced by a fetus' liver that can be found in the amniotic fluid and in the mother's blood. Abnormally high levels of this substance suggests there may be defects in the fetal neural tube, a structure that will include the brain and spinal cord when completely developed. Abnormally low levels suggest the possibility of Down' syndrome.
Braxton Hicks' contractions— Short, fairly painless uterine contractions during pregnancy that may be mistaken for labor pains. They allow the uterus to grow and help circulate blood through the uterine blood vessels.
Chloasma— A skin discoloration common during pregnancy, also known as the "mask of pregnancy" or melasma, in which blotches of pale brown skin appear on the face. It is usually caused by hormonal changes. The blotches may appear in the forehead, cheeks, and nose, and may merge into one dark mask. It usually fades gradually after pregnancy, but it may become permanent or recur with subsequent pregnancies. Some women may also find that the line running from the top to the bottom of their abdomen darkens. This is called the linea nigra.
Embryo— An unborn child during the first eight weeks of development following conception (fertilization with sperm). For the rest of pregnancy, the embryo is known as a fetus.
Fetus— An unborn child from the end of the eights week after fertilization until birth.
Human chorionic gonadotropin (hCG)— A hormone produced by the placenta during pregnancy.
Placenta— The organ that develops in the uterus during pregnancy that links the blood supplies of the mother and baby.
Rhythm method— The oldest method of contraception with a very high failure rate, in which partners periodically refrain from having sex during ovulation. Ovulation is predicted on the basis of a woman's previous menstrual cycle.
Spina bifida— A congenital defect in which part of the vertebrae fail to develop completely, leaving a portion of the spinal cord exposed.
There are many ways to avoid pregnancy. A woman has a choice of many methods of contraception which will prevent pregnancy, including (in order of least to most effective):
Healthy Mothers, Healthy Babies National Coalition. 409 12th St., Washington, DC 20024. (202) 638-5577.
National Institute of Child Health and Human Development. 9000 Rockville Pike, Bldg. 31, Rm. 2A32, Bethesda, MD 20892. (301) 496-5133.
Positive Pregnancy and Parenting Fitness. 51 Saltrock Rd., Baltic, CT 06330. (203) 822-8573.
Planned Parenthood. 〈http://www.plannedparenthood.org〉.
Pregnancy Information. 〈http://www.childbirth.org〉.
Gordon, Debra. "Pregnancy." Gale Encyclopedia of Medicine, 3rd ed.. 2006. Encyclopedia.com. (May 22, 2013). http://www.encyclopedia.com/doc/1G2-3451601304.html
Gordon, Debra. "Pregnancy." Gale Encyclopedia of Medicine, 3rd ed.. 2006. Retrieved May 22, 2013 from Encyclopedia.com: http://www.encyclopedia.com/doc/1G2-3451601304.html
A great deal of public health resources is spent on pregnancy. It is clear that prenatal and neonatal health play a large role in determining the health of a population, and in fact, pregnancy outcomes are often used as an indicator of a nation's health.
EPIDEMIOLOGY OF PREGNANCY
Globally, there are approximately 240 million pregnancies annually. These pregnancies result in 134 million births and 50 million induced abortions, 20 million of which are performed under unsafe conditions. Approximately 6 to 7 million of these 240 million pregnancies occur each year in the United States. These result in about 4 million liveborn babies, over 1 million induced abortions, at least 1 million spontaneous abortions (miscarriages), nearly 100,000 ectopic pregnancies (a pregnancy in which the fetus develops outside the uterus), and about 30,000 fetal deaths.
Of the 4 million babies born in the United States in 1999, 12 percent were born to women under 20 years of age. Approximately 4.5 percent of white teens (ages 15 to 19), 8.1 percent of African-American teens, and 9.3 percent of Hispanic teens gave birth. Since 1991, the teenage birth rate has been declining in the United States, particularly among African Americans, largely because of an increased use of effective contraception.
In 1999, 13 percent of the babies born in the United States were born to women 35 years old and older. The birth rate among this age group increased during the last three decades of the twentieth century, despite the fact that older women have an increased risk for having babies with chromosomal abnormalities (the risk is approximately 1 in 1,000 at age 25, 1 in 200 at age 35, and 1 in 20 at age 45).
About half of all pregnancies are unintended or unplanned, and one in three babies are born to single or unmarried mothers. (Nearly 70% of African-American babies and over 40% of Hispanic babies are born to unmarried mothers.)
Four out of five women who gave birth in 1999 started prenatal care in the first trimester, though this percentage was lower among African-American and Hispanic women. Despite an overall improvement in prenatal care utilization, the proportion of low birthweight (LBW) births and preterm births have been increasing gradually since the mid-1980s. This increase is accounted for, in part, an increase in multiple gestations and the growing number of infants born to women older than 35 years of age.
Of the 1.2 million legal induced abortions performed in 1999, 20 percent were obtained by women less than 20 years old, 60 percent by white women, and 80 percent by unmarried women.
PHYSIOLOGY OF PREGNANCY
A human pregnancy starts when the male sperm fertilizes the ovum (egg) in a woman's Fallopian tube, and it lasts, on average, 266 days. Contraception works by inhibiting the release of the ovum from the ovary (birth control pill, injectible, or subdermal implant), by impeding the release of sperm (vasectomy), by blocking sperm from entering the vagina or cervix (male or female condom, diaphragm, or cervical cap), or by blocking the Fallopian tubes (tubal ligation). Once conception takes place, the fertilized egg travels through the Fallopian tube into the uterus, where it implants about seven days later. The intrauterine device (IUD) impedes such implantation, and medications like mifepristone (RU486) causes the implanted embryo to abort.
A developing human is called an embryo between two and eight weeks after conception; thereafter it is called a fetus until delivery. Development of the major organs begins during the early embryonic period, and interference with this process may result in birth defects. Women taking harmful substances, or women with preexisting diseases like diabetes mellitus, are at increased risk for having babies with birth defects. Because the development of major organs begins during early pregnancy, often before a woman starts prenatal care or realizes that she is pregnant, preconceptional care is recommended for every woman of reproductive age.
Although most major organs are present at the end of the embryonic period, the development of their functions continues well into the fetal period, infancy, and early childhood. Interference with this process may lead to functional deficits. For example, undernutrition during this period of growth has been associated with increased risk for coronary heart disease, and maternal alcohol use during pregnancy has been linked to mental retardation and other birth defects.
Remarkable changes take place in a woman during pregnancy. The heart circulates 40 percent more blood volume to supply nutrients and oxygen to the growing baby, deeper breaths occur and an increased amount of harmful substances are cleansed through the kidneys. Digestion slows down for better absorption or nutrients, which may cause problems such as heartburn and constipation. The baby is sustained in the uterus by the placenta, which serves as the interface between maternal and fetal circulations. Hormones prepare the breasts for lactation, and the immune system is altered so that it does not reject the baby as a foreign body. While most healthy women make these adaptations readily, pregnancy can jeopardize the health, and sometimes the lives, of women who are less healthy and suffer increased stress to the system during pregnancy.
PATHOPHYSIOLOGY OF PREGNANCY
When things go wrong during pregnancy, the health of both mother and baby may be at risk of certain health problems associated with pregnancy.
Infertility. Infertility is defined as failure to conceive following a period of 12 months or longer of unprotected sexual intercourse. In 1988, over 8 million American women 15 to 44 years of age reported an impaired ability to have children. Major causes include endometriosis, poor sperm quality or low sperm count, failure to ovulate, and tubal damage.
Ectopic Pregnancy. An ectopic pregnancy is a pregnancy that has implanted outside of the uterus, most commonly in the Fallopian tubes, which may have been scarred from a previous infection, ectopic pregnancy, or tubal ligation. The growing pregnancy, if not surgically terminated, may rupture the tube, causing hemorrhage. Ectopic pregnancy is a leading cause of maternal deaths among African-American women.
Abortion. Abortion refers to the termination of pregnancy before the twentieth week of gestation (counting from the last menstrual period). Abortion can be spontaneous or induced. Most spontaneous abortions (miscarriages) involve some chromosomal abnormalities; the causes of the rest are not known, but some may be due to exposure to environmental toxins.
Birth Defects. Birth defects are the leading cause of infant death and the fifth leading cause of potential years of life lost. About 3.6 percent of all babies in the United States are born with major birth defects, the most common being cleft lip and palate, Down syndrome, neural tube defect, and congenital heart disease.
Low Birth Weight (LBW). LBW, defined as birth weight under 2,500 grams (5.5 pounds), is the second leading cause of infant death, and the leading cause of infant death among African Americans. Risk factors include short interpregnancy interval, low prepregnancy weight, inadequate weight gain during pregnancy, history of LBW or preterm birth, cigarette smoking, and socioeconomic factors.
Preterm Birth. Preterm birth, defined as delivery before 37 weeks of gestation, may result in major problems, including neurological damage from brain hemorrhage or respiratory distress from immature lungs.
Fetal Death. Fetal death refers to the death of a fetus after 20 weeks of gestation. Major causes include preexisting maternal conditions like diabetes mellitus or hypertension, and premature separation of the placenta from the uterus (placental abruption) as a result of drug use or trauma.
Infant Death. Infant death refers to death of a baby under one year of age. Major causes include birth defects, LBW, and sudden infant death syndrome (SIDS).
Maternal Death. Maternal death is defined as the death of a woman as a result of her pregnancy, from the first stages of gestation to within 42 days after the pregnancy has terminated. Risk factors include age greater than 35, unmarried status (owing to socioeconomic factors, including a lack of access to health care), and lack of prenatal care. The classic HIT triad (hemorrhage, infection, and toxemia or preelcampsia) contributes to about half of all maternal deaths. Approximately 300 women in the United States and 500,000 women in the world die every year from pregnancy-related causes. The maternal mortality ratio of 7.5 deaths per 100,000 live births in the United States did not changed significantly during the last 20 years of the twentieth century.
Preeclampsia. Preeclampsia, caused by high blood pressure during the latter part of pregnancy, is characterized by hypertension, protein in the urine, edema, and organ damage as a result of hypertension. Such organ damage may include seizure, stroke, kidney failure, liver damage, and fluid in the lungs. Preeclampsia is treated by effecting prompt delivery (and thereby ridding the body of the circulating toxin released by the placenta). Magnesium is commonly used to prevent seizure. Complications of severe preeclampsia can often be prevented with early diagnosis and appropriate treatment.
Obstetrical Hemorrhage. Obstetrical hemorrhage is characterized by excessive blood loss. It occurs prenatally as a result of premature separation (placental abruption) or abnormal location (placenta previa) of the placenta. It can also occur as a result of injury to the birth canal during delivery, retained placenta within the uterus after delivery, or the inability of the uterus to firm up (uterine atony) after delivery.
Puerperal Infection. Puerperal infections are those that occur during labor, delivery, or the postpartum period. The infection is typically caused by bacteria from the vagina ascending into the uterus. Risk factors include cesarean section, prolonged time from when the "water breaks" to delivery, poor nutrition, and maternal anemia. Prompt treatment with antibiotics can prevent significant morbidity associated with puerperal infections.
Embolism. An embolus is a clot. It could be a blood clot (thromboembolus), or a clot of fetal tissues (amniotic fluid embolus) that travels in maternal circulation. If it blocks off circulation in the lungs or the heart, the embolus could be fatal.
Between 1900 and 2000, infant mortality in the United States declined by 90 percent, and maternal mortality by 99 percent. This was one of the greatest achievements of public health in the twentieth century. However, the goal, established in 1994 by the International Conference on Population and Development, of every pregnancy being healthy has not been achieved. Current efforts to ensure healthy pregnancy work at three different levels of prevention.
Primary prevention involves efforts to prevent diseases from occurring during pregnancy. Examples of primary prevention during pregnancy include family planning, preconceptional care, and health promotion during prenatal care. By preventing unintended pregnancies, family planning can prevent morbidity associated with unintended pregnancies. Preconceptional care has been shown to reduce certain birth defects. Proper nutrition and cessation of tobacco, alcohol, and drug use during pregnancy can prevent low birth weight and other complications.
Secondary prevention involves efforts to facilitate early detection and treatment of diseases during pregnancy. Prenatal care provides early and continuous assessment of the pregnant woman, and includes early detection of preeclampsia, syphilis, and tuberculosis.
Tertiary prevention attempts to avert severe complications resulting from diseases during pregnancy. Examples of tertiary prevention include the administration of antibiotics in the treatment of puerperal infection, magnesium to prevent eclampsia (convulsions) in women affected by severe preeclampsia, and transfusion of blood products when obstetrical hemorrhage occurs. Regionalization of perinatal health services, so that high-risk women deliver only in hospitals equipped to deal with potential complications, plays an important role in tertiary prevention.
Much of the improvement in maternal and infant health is attributable to improved health conditions such as better sanitation, sewage control, and safer water supplies. Continued improvement is likely to come from social and behavioral changes rather than from advancement in medical care. Such developments as the expansion in the availability of legal abortions, increased education for women, and better family planning practices have all contributed to improved maternal and infant health. It is important, therefore, for public health professionals to learn how to better address social and behavioral determinants of health. For example, because smoking cigarettes during pregnancy can cause low birth weight and prematurity, it is important to find out how to stop women from smoking during pregnancy.
Because the health of a baby is tied to health of the mother, efforts to improve pregnancy outcomes must begin with women's health. Current efforts fall short by doing too little too late—to expect prenatal care to reverse all the cumulative effects of risk exposures over the course of a woman's life may be expecting too much. Future efforts should promote health not only during pregnancy, but during all of a woman's life.
Michael C. Lu
(see also: Abortion; Abortion Laws; Birthrate; Child Health Services; Child Mortality; Contraception; Family Health; Family Planning Behavior; Fecundity and Fertility; Fetal Alcohol Syndrome; Fetal Death; Folic Acid; Infant Mortality Rate; Maternal and Child Health; Newborn Screening; Planned Parenthood; Prenatal Care; Reproduction; Women's Health )
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Brown, S. S, and Eisenberg, L., eds. (1995). The Best Intentions: Unintended Pregnancy and the Well-Being of Children and Families. Washington, DC: National Academy Press.
Centers for Disease Control and Prevention (2000). "Abortion Surveillance: Preliminary Analysis—United States, 1997." Morbidity and Mortality Weekly Report 48:1171–1174.
Cunningham, F. G.; MacDonald, P. C.; Gant, N. F.; Leveno, K. J.; and Gilstrap, L. C. (1997). Williams Obstetrics, 20th edition. Norwalk, CT: Appleton & Lange.
Curtin, S. C., and Martin, J. A. (2000). "Births: Preliminary Data for 1999." National Vital Statistics Reports 48:14. Hyattsville, MD: National Center for Health Statistics.
Moore, K. L. (1988). Essentials of Human Embryology. Toronto: Decker.
Smedley, B. D., and Syme, S. L., eds. (2000). Promoting Health: Intervention Strategies from Social and Behavioral Research. Washington, DC: National Academy Press.
Lu, Michael C.. "Pregnancy." Encyclopedia of Public Health. 2002. Encyclopedia.com. (May 22, 2013). http://www.encyclopedia.com/doc/1G2-3404000677.html
Lu, Michael C.. "Pregnancy." Encyclopedia of Public Health. 2002. Retrieved May 22, 2013 from Encyclopedia.com: http://www.encyclopedia.com/doc/1G2-3404000677.html
pregnancy The biological event of pregnancy is established when a fertilized egg successfully implants itself in the lining of the uterus, about a week after conception.
The corpus luteum, which formed in the ovary when it released the egg, secretes hormones that keep the uterine lining in a suitable state for implantation; if fertilization had not occurred, this hormone secretion would have ceased, and the uterine lining would be shed after two weeks. The hormonal ‘message’ from an implanted embryo via the mother's bloodstream to the ovary prevents its own rejection.
Early pregnancy continues to be maintained by the hormones produced by the corpus luteum in the ovary that produced the egg; but later, when the placenta has fully developed (by about 3 months), this takes over the maintenance function through its own hormone production.
Pregnancy produces profound changes in the mother, which may be detected from early stages. There is a marked rise in the output of the heart by 3 months, and it rises further as pregnancy advances, reaching 30–40% above the non-pregnant level by the end. This rise is mainly due to an increase in output with each contraction of the heart muscle (stroke volume), although the heart rate also increases. The volume of blood in the circulation also increases, with a greater increase in plasma volume than in red blood cells, producing the so-called ‘physiological anaemia of pregnancy’. Although these changes in the circulation can produce serious consequences for pregnant women with certain types of heart disease, they are necessary to deal with the demands of the growing fetus, placenta, and uterus, and have no deleterious effects in healthy mothers.
There are changes in the breasts from an early stage of pregnancy; they enlarge, and surface blood vessels become prominent, reflecting preparation for eventual lactation. Hormonal changes cause development of the glandular tissue: the potential milk-secreting cells and the ducts to the nipples. Although the hormones which cause milk production (prolactins) are produced during pregnancy, the actual secretion of milk is suppressed by other hormones until after delivery.
Other changes include a laxity of the joints, which ultimately may assist labour and birth, and increased brown pigmentation of the skin (‘chloasma’ if in the face). Stretch marks are other hallmarks of pregnancy in the skin. The mother has increased blood flow to the kidneys, and therefore increased urine production, and this results in more frequent visits to the toilet — a common symptom of early pregnancy. The placenta produces large amounts of the hormone progesterone, which appropriately prevents the uterine smooth muscle from contracting, but also relaxes smooth muscle throughout the body. This results in many of the so-called minor symptoms of pregnancy, including constipation and heartburn, and it may exacerbate varicose veins.
The mother's appetite usually increases — but the extra energy requirement for the whole pregnancy is not more than about 60 000 Kcal — or 20–24 extra days' worth of food intake. Where there is abundance of food, excessive eating and undue weight gain are not uncommon, although there is in fact a normal physiological tendency to lay down more fat stores in the earlier months. Appetite for particular foods and drinks, or rejection of others, can be capricious. Occasionally the nausea of morning sickness, which is common in early pregnancy, may extend to other times of day, may be more severe than usual, and may be accompanied by vomiting or may be prolonged into later pregnancy.
The uterus enlarges considerably to accommodate the growing fetus. It emerges from the pelvis at around 12 weeks, reaches the navel at around 22 weeks, and the ribs at around 36 weeks.
Pregnancy normally reaches its dramatic conclusion with the onset of labour, between 35 and 39 weeks after conception.
The establishment of antenatal care to detect problems during pregnancy, and to attempt to ensure that women were in good health at the time of delivery, is generally credited to J. W. Ballantyne, an Edinburgh obstetrician, who took the first step towards this at the beginning of the twentieth century. Clinics became established in major centres in the UK, the US, and Australia by the time of the first World War.
Pregnancy: the cultural contextPregnancy occupies potent symbolic space in cultures around the world. As both the development of a life and a significant transitional event within the woman's lifespan, pregnancy becomes the focus of cultural desires and anxieties around gender, power, selfhood, and even nationhood. Medical technology has increasingly refigured the physiological possibilities of pregnancy, especially through assisted reproduction for the infertile, its extensions to surrogacy and older-age pregnancy, and through genetic testing.
One of the most common cultural mythologies about pregnancy is that it is evidence of full womanhood. Because mothering is so closely tied into cultural gender roles, to be pregnant is to fulfill one's gendered destiny. Although this emphasis on pregnancy emerges from culturally-specific definitions of femininity and womanhood, many people see the urge as instinctive and the process itself as natural, even as industrialized countries increasingly rely on medical technologies to avoid, create, sustain, and complete pregnancies.
Differential worldwide rates of fertility, infant mortality, and maternal mortality have led the World Health Organization to focus attention on women's differential access to services and opportunities with respect to men as well as between different countries and regions. At least partly because of this focus, all three of these rates dropped by about one-third over the twenty years up to 1998, when overall fertility rate was 2.7 births per woman; Europe was lowest at 1.6, while Africa remained highest at 5.4. Infant mortality rate world-wide was 57 deaths per 1000 live births, whereas highly industrialized countries such as the US and the UK had rates as low as 7 deaths per 1000. Maternal mortality rate (expressed as deaths per 100 000 births) in the UK showed a dramatic drop from the 1930s onwards, whereas until then it had been essentially unchanged at around 500 for 100 years; in the 1980s it was below 10. By the end of the twentieth century, according to the World Health Organization, developed nations averaged a rate of 27 deaths per 100 000 live births. This contrasts with 480 on average in developing nations (comparable to Victorian Britain), with some regions as high as 1000. The global average was 430. While these numbers are specific to pregnancy, and associated with disparities in medical services and supplies, they may also reflect the status of girls and women in different cultures, and their relative power in their societies.
Pregnancy, in the natural order of things, becomes possible and physiologically appropriate as soon as ovulation is established after the menarche, usually during the teens, or even earlier. But in modern developed societies, the issue of teenage pregnancy is increasingly a concern to both moral leaders and health educators. In the UK the rate has been rising: in 1997, under-16s accounted for over 8% of all known conceptions in the under-20 age group; meanwhile rates declined in other European countries and in the US there has been some reduction since the late 1980s. The spectre of the pregnant young girl is often cited as a wake-up call for issues as diverse as promiscuity, health education, and the viability of the welfare state.
Young women who maintain pregnancies are less likely to finish or continue their education, face greater marital instability, have fewer lifelong assets, and have lower incomes later in life than women who did not become pregnant young. Yet pregnant teenagers have become symbolic more of the decline of social morality than of the lack of resources granted to young women worldwide.
Teenage and unmarried pregnancies have always existed, but the advent of new methods of contraception in the twentieth century has changed the significance and experience of pregnancy for hundreds of millions of women worldwide. Before these methods were widely and legally available, pregnancy often signified the end of a woman's career choices, if not her need to work; closely successive pregnancies, when timing could not be controlled, often led to early death, as it still does in many places worldwide today.
Female-directed methods, such as the modern intrauterine device (IUD) and hormonal control by the Pill or by long-lasting implants, have allowed women to choose not only the occurrence but also the timing of pregnancy. Earlier barrier methods of contraception had allowed women to control their pregnancies somewhat, although they also required them to negotiate with their husbands. Hormonal contraceptives have changed many women's relationship to pregnancy by putting the choice in their own hands. Indeed, world health leaders are calling for this globally as a step towards women's liberation from socially imposed controls.
As women have been afforded more control over pregnancy, they have also been granted more responsibility for the outcomes. European societies of the seventeenth and eighteenth centuries often assumed that strong maternal emotions would mark the fetus; disfigured babies were blamed on maternal viewing of disfigured persons or other disturbing events. Modern versions of maternal responsibility relate to the links between birth outcomes and maternal behaviors, such as drinking alcohol, smoking cigarettes, or taking drugs (licit or illicit). Whilst high risks for fetal abnormality are established for some maternal excesses (e.g. alcohol, cocaine), for specific nutritional deficiencies (some vitamins and trace elements), and for certain prescription drugs, prohibitions and exhortations may often be overstated. While women around the world and through time have made sacrifices and personal changes for the good of the fetus, this modern focus on risk and risk management has defined what constitutes ‘the good of the fetus’. The rights of women to bodily integrity and self-determination seem sometimes to be undermined by a society's concern to protect the fetus from any possibility of harm.
In the latter half of the twentieth century also, medical technologies began to address infertility, and to develop methods of assisted reproduction. These have not only benefited childless couples, but have also resulted in extensions of pregnancy in two other contexts. Surrogacy, the creation and carrying of a pregnancy for another woman or couple, has gained both prominence and notoriety in recent years. The practice has spawned high-profile custody cases, the most famous of which is the Mary Beth Whitehead case, as well as more prosaic cases of women carrying babies for their sisters, daughters, and friends — as demonstrated in Sisters, US television drama. While this has created legal disputes about the relative importance of genetic parenthood over physical parenthood, it has also enabled infertile couples, including lesbian couples, to create genetically-connected families.
The medical procedures involved in surrogacy — hormone treatments, ova extraction, in-vitro fertilization (IVF), and gamete intrafallopian tube transfer (GIFT), for example — have also allowed post-menopausal women to bear children. A number of cases have recently occurred in the US, where several women in their 50s and 60s have given birth. These events touched off a national debate about appropriate motherhood and the dual pressures towards a career and a family that modern women often face.
Even routine pregnancies in industrialized countries are increasingly technological, as couples are offered genetic counselling, and ultrasound scans and amniocentesis have become commonplace. While these procedures can sometimes highlight problems that medical technology can successfully address, they may create anxiety through false positives, nebulous results, and the construction of pregnancy as problematic, instead of generally successful. While technology has long been able to transform, and has often usefully assisted the procedure of birth, these diagnostic procedures have only recently allowed the medical profession immediate and even cellular control over the management of pregnancy.
Pregnancy is essentially a personal event, but international attention is currently focusing on pregnancy around the world. While the World Health Organization is focused on lowering rates of fertility, infant mortality, and maternal mortality in order to improve the lives of women and children, national concern for differential pregnancy rates frequently betrays racist undertones; industrialized countries, and well-off populations within them, worry about how ‘they’ will outnumber and overtake ‘us’. Although often categorized as a ‘woman's issue’, pregnancy and the social attitudes towards it thus highlight important cultural issues, such as the relationship between life and technology, the definitions of gender roles in a given society, and the relationship between nations and their citizens.
See also antenatal development; assisted reproduction; birth; contraception; fertility; infertility; labour; ovaries; placenta; sex hormones; uterus.
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COLIN BLAKEMORE and SHELIA JENNETT. "pregnancy." The Oxford Companion to the Body. 2001. Retrieved May 22, 2013 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O128-pregnancy.html
pregnancy, period of time between fertilization of the ovum (conception) and birth, during which mammals carry their developing young in the uterus (see embryo). The duration of pregnancy in humans is about 280 days, equal to 9 calendar months. After the fertilized ovum is implanted in the uterus, rapid changes occur in the reproductive organs of the mother. The uterus becomes larger and more flexible, enlargement of the breasts begins, and alteration of renal function, blood volume, and blood cell count occur. Movement of the fetus and fetal heartbeat can be detected early in pregnancy.
See J. T. Queenan and C. N. Queenan, ed. A New Life (1992); C. A. Bean, Methods of Childbirth (1990);; Boston Women's Health Book Collective, Our Bodies, Ourselves for the New Century (1998).
"pregnancy." The Columbia Encyclopedia, 6th ed.. 2013. Encyclopedia.com. (May 22, 2013). http://www.encyclopedia.com/doc/1E1-pregnanc.html
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"Pregnancy." -Ologies and -Isms. 1986. Encyclopedia.com. (May 22, 2013). http://www.encyclopedia.com/doc/1G2-2505200338.html
"Pregnancy." -Ologies and -Isms. 1986. Retrieved May 22, 2013 from Encyclopedia.com: http://www.encyclopedia.com/doc/1G2-2505200338.html
pregnancy (preg-năn-si) n. the period during which a woman carries a developing fetus, normally in the uterus (compare ectopic pregnancy). Pregnancy lasts for approximately 266 days, from conception until the baby is born, or 280 days from the first day of the last menstrual period (see Naegele rule). See also pseudocyesis (phantom pregnancy). p. test any of several methods used to demonstrate whether or not a woman is pregnant. Most pregnancy tests are based on the detection, by immunological methods, of a hormone, human chorionic gonadotrophin, in the urine or in the serum.
—pregnant adj.www.bbc.co.uk/parenting/having_a_baby/pregnancy_index.shtml Details of pregnancy from a BBC website
"pregnancy." A Dictionary of Nursing. 2008. Encyclopedia.com. (May 22, 2013). http://www.encyclopedia.com/doc/1O62-pregnancy.html
"pregnancy." A Dictionary of Nursing. 2008. Retrieved May 22, 2013 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O62-pregnancy.html
pregnancy Period of time from conception until birth, in humans normally c.40 weeks (280 days). It is generally divided into three 3-month periods called trimesters. In the first trimester, the embryo grows from a small ball of cells to a fetus c.7.6cm (3in) in length. At the beginning of the second trimester, movements are first felt and the fetus grows to about 36cm (14in). In the third trimester, the fetus attains its full body weight. See also labour
"pregnancy." World Encyclopedia. 2005. Encyclopedia.com. (May 22, 2013). http://www.encyclopedia.com/doc/1O142-pregnancy.html
"pregnancy." World Encyclopedia. 2005. Retrieved May 22, 2013 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O142-pregnancy.html
preg·nan·cy / ˈpregnənsē/ • n. (pl. -cies) the condition or period of being pregnant: the first weeks of pregnancy. ∎ a case or situation of being pregnant: a straightforward pregnancy.
"pregnancy." The Oxford Pocket Dictionary of Current English. 2009. Encyclopedia.com. (May 22, 2013). http://www.encyclopedia.com/doc/1O999-pregnancy.html
"pregnancy." The Oxford Pocket Dictionary of Current English. 2009. Retrieved May 22, 2013 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O999-pregnancy.html
pregnancy See gestation.
"pregnancy." A Dictionary of Biology. 2004. Encyclopedia.com. (May 22, 2013). http://www.encyclopedia.com/doc/1O6-pregnancy.html
"pregnancy." A Dictionary of Biology. 2004. Retrieved May 22, 2013 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O6-pregnancy.html
pregnancy •radiancy •immediacy, intermediacy •expediency • idiocy • saliency •resiliency • leniency •incipiency, recipiency •recreancy • pruriency • deviancy •subserviency • transiency • pliancy •buoyancy, flamboyancy •fluency, truancy •constituency • abbacy • embassy •celibacy • absorbency •incumbency, recumbency •ascendancy, intendancy, interdependency, pendency, resplendency, superintendency, tendency, transcendency •candidacy •presidency, residency •despondency • redundancy • infancy •sycophancy • argosy • legacy •profligacy • surrogacy •extravagancy • plangency • agency •regency •astringency, contingency, stringency •intransigency • exigency • cogency •pungency •convergency, emergency, insurgency, urgency •vacancy • piquancy • fricassee •mendicancy • efficacy • prolificacy •insignificancy • delicacy • intricacy •advocacy • fallacy • galaxy •jealousy, prelacy •repellency • valency • Wallasey •articulacy • corpulency • inviolacy •excellency • equivalency • pharmacy •supremacy • clemency • Christmassy •illegitimacy, legitimacy •intimacy • ultimacy • primacy •dormancy • diplomacy • contumacy •stagnancy •lieutenancy, subtenancy, tenancy •pregnancy •benignancy, malignancy •effeminacy • prominency •obstinacy • pertinency • lunacy •immanency •impermanency, permanency •rampancy • papacy • flippancy •occupancy •archiepiscopacy, episcopacy •transparency • leprosy • inerrancy •flagrancy, fragrancy, vagrancy •conspiracy • idiosyncrasy •minstrelsy • magistracy • piracy •vibrancy •adhocracy, aristocracy, autocracy, bureaucracy, democracy, gerontocracy, gynaecocracy (US gynecocracy), hierocracy, hypocrisy, meritocracy, mobocracy, monocracy, plutocracy, technocracy, theocracy •accuracy • obduracy • currency •curacy, pleurisy •confederacy • numeracy •degeneracy • itinerancy • inveteracy •illiteracy, literacy •innocency • trenchancy • deficiency •fantasy, phantasy •intestacy • ecstasy • expectancy •latency • chieftaincy • intermittency •consistency, insistency, persistency •instancy • militancy • impenitency •precipitancy • competency •hesitancy • apostasy • constancy •accountancy • adjutancy •consultancy, exultancy •impotency • discourtesy •inadvertency • privacy •irrelevancy, relevancy •solvency • frequency • delinquency •adequacy • poignancy
"pregnancy." Oxford Dictionary of Rhymes. 2007. Encyclopedia.com. (May 22, 2013). http://www.encyclopedia.com/doc/1O233-pregnancy.html
"pregnancy." Oxford Dictionary of Rhymes. 2007. Retrieved May 22, 2013 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O233-pregnancy.html