Of all the ways in which childhood has changed since premodern times, perhaps the most significant has been the dramatic decrease in the likelihood of dying during the first year of life. Although we can only estimate levels and trends of infant mortality prior to the most recent centuries, it seems probable that through much of human history 30 to 40 percent of all infants born died before they could celebrate their first birthdays. Today, in even the most underdeveloped and high-mortality regions of the world, barely a tenth do. And in the most developed and wealthiest regions less than 1 percent of infants fail to survive their first year. The vast majority of this sharp reduction in infant mortality took place in the twentieth century. Among today's highly developed nations, the major improvement in infant survival came prior to World War II. In the less developed nations, almost all the improvement has come since the war. In both sets of nations, mortality first dropped among older infants and then only later, if at all, among newborns.
Measuring Infant Mortality
The term infant mortality is generally understood to refer to the incidence of death among infants less than one year of age. When demographers attempt to chart the levels and trends of that mortality, they employ a number of statistics, most notably infant, neonatal, and post-neonatal mortality rates. These are standardized measures unaffected by differences in the proportion of infants in a given population. The infant mortality rate is the annual number of deaths among infants less than one year old per thousand live births. This measure is similar but not identical to what is called the infant death rate, which is the ratio of infant deaths to infants living and is somewhat higher. The neonatal mortality rate is calculated as the annual number of deaths of infants less than twenty-eight days old per hundred thousand live births. It is generally accepted that most of the deaths during this period are from endogenous causes; that is from congenital anomalies, gestational immaturity, birth complications, or other physiological problems. The post-neonatal mortality rate is computed similarly but describes the death rate of infants twenty-eight days to one year. In much of the world, the vast majority of deaths during this period continue to be from exogenous causes; that is, from injuries and from environmental and nutritional factors, especially as they interact with infectious disease like gastroenteritis and pneumonia. In the more highly developed nations, however, control of infectious disease and nutritional disorders has reached such a level that an ever-increasing proportion of post-neonatal deaths are attributable to endogenous causes.
Infant Mortality in the Developed Nations before the Twentieth Century
What we know about the historical mortality patterns of today's highly developed nations suggests that through the seventeenth century infant mortality averaged between 20 and 40 percent and fluctuated substantially from year to year, occasionally hitting extremely high peaks when epidemics, famines, and war created mortality crises for the general population. Highly dependent on levels of maternal nutrition and general health as well as on the local sanitary and disease environments, infant mortality also varied significantly from place to place. In isolated rural villages in seventeenth-century England and New England, as few as 15 percent of all infants born may have perished in their first year. At the same time, their counterparts born in seaports, where sanitation was poor and where there was commerce in people, goods, and infectious diseases, probably died at over twice that rate. In the Americas and in southern Europe the presence of malaria could push infant mortality to over 50 percent. So too could the introduction of new diseases. Following the arrival of Europeans and then Africans in the New World, the aboriginal populations of the Americas were decimated by exposure to diseases to which they had no acquired or inherited immunities. In short, nothing so characterized levels of infant mortality in the premodern era as their variability across time and place.
That variability continued into the early eighteenth century, when the yearly fluctuations began to decrease, the periodic peaks became less frequent, and the differences between localities diminished. In a few places, a slight secular downward trend took place, but for the most part the period saw the stabilization rather than the lowering of infant mortality. Contributing to the homogenization and stabilization of infant mortality rates were the concomitants of economic development. Improvements in transportation made travel to rural villages less difficult and time consuming, increasing the communication of diseases from place to place and thus decreasing the likelihood that isolated pockets of low infant mortality could exist. Better urban sanitation, improvements in housing, and the more even distribution of foodstuffs, the filling and draining of swamps, and, perhaps, a world-wide southward retreat of malaria all helped make it less true for infants that being born in certain years and certain places constituted a death threat that would be enacted within a year's time. Of course, variability by time and place did not disappear; it only decreased. Seaports and cities were still
more inimical to infant life than the countryside. And epidemics of smallpox, yellow fever, and other infectious diseases could still produce spikes of infant and general mortality. Additionally, considerable evidence exists that cultural differences in child rearing–particularly infant feeding practices–may have contributed significantly to higher rates in some areas than others.
The trend toward stabilization and conformity continued until the effects of early industrialization and urbanization began to be felt in the mid- to late eighteenth century. Industrialization brought increased wealth and higher living standards, but it also created industrial towns and massive cities which contained a significant underclass whose health was compromised by the social and biological pathologies that attend grinding poverty and filthy, overcrowded, disease-infested urban slums. For infants, it seems that initially the positive consequences of industrialization outweighed the negative ones. Although the evidence is not abundant, it is probable that infant survival improved in England through the third quarter of the eighteenth century and in western Europe and the United States during the forty years following 1790. It is also probable that by the middle of the nineteenth century, infant mortality rates were rising again as urbanization, industrialization, and the migration of workers and their families worsened sanitation and environmental pollution, made infant care more difficult, and increased the likelihood that pregnant women and infants would be exposed to dangerous diseases or toxins.
Indeed, late-nineteenth-century cities and industrial towns were deadly locales for infants, where 20 to 35 percent of all those born died within twelve months and where summer epidemics of gastroenteritis and diarrhea turned densely packed neighborhoods into infant abattoirs. As the New York Times editorialized in 1876 after one particularly deadly July week in which over a hundred infants a day had died in Manhattan: "There is no more depressing feature about our American cities than the annual slaughter of little children of which they are the scene" (quoted in Meckel, p. 11). Growing public concern throughout the industrialized West over this annual slaughter helped precipitate a public health movement to improve infant health and survival. Along with a complex amalgam of socioeconomic, environmental, and medical developments at the end of the nineteenth century, that movement started infant and child death rates on the path of decline that they would follow through the twentieth century and into the twenty-first.
The Twentieth-Century Decline of Infant Mortality in the Developed World
As the twentieth century opened, infant mortality throughout much of the industrialized world had begun to drop. Nevertheless infant survival was still precarious, especially in eastern Europe. As table 1 shows, the probability of dying in infancy ranged from less than 10 percent in Scandinavia to over 22 percent in Austria, Czechoslovakia, and European Russia. In the United States the rate was approximately 12 percent. By the middle of the twentieth century it had declined significantly. In North America, northern Europe, and Australia it was less than 3 percent. In western Europe it was less than 5 percent and in eastern and southern Europe less than 9 percent. Much of that decline came among post-neonates, initially from a reduction in gastroenteric and diarrheal disorders and then from control of respiratory diseases.
Behind this reduction lay several developments. Prior to the 1930s, declining fertility and better nutrition and housing, accompanied by a rising standard of living, played important roles in reducing infant mortality. So too did environmental improvements brought about by the publicly funded construction of sanitary water supply and sewage systems and the implementation of effective refuse removal, particularly in urban areas. Also crucial was the work of public health officials and their allies in medicine and social work in controlling milk-borne diseases and educating the public in the basics of preventive and infant hygiene. Indeed, in the first three decades of the twentieth century, all the industrial nations of the world were the sites of major public health campaigns aimed at dramatically reducing infant mortality.
For many of the same reasons that it declined during the first third of the century, infant mortality continued to fall during the second. However, beginning in the 1930s the development and application of medical interventions and technologies played an increasingly large role in driving down infant death rates. Particularly important were the development, production, and dissemination of effective immunizations and drug therapies to combat the incidence and deadliness of infectious and parasitic diseases. Also important were significant improvements in both the techniques and technologies available to manage or correct life-threatening diseases or health problems. Among the most important of these were the perfection and widespread us of electrolyte and fluid therapy to counter the acidosis and dehydration that is often a consequence of serious bouts of diarrhea and enteritis; the increasingly sophisticated preventive and therapeutic use of vitamins to aid metabolism and combat nutritional diseases; and the development of increasingly safe and effective obstetric and surgical techniques to facilitate problem births and correct the consequences of congenital malformations.
In the last third of the twentieth century, the decline of mortality among older infants slowed to a snail's pace. Among neonates, however, it quickened precipitously, falling over 50 percent in some developed nations. Driving neonatal mortality down was an intense international effort to develop and make widely available various sociomedical programs and specific techniques and technologies to increase the survival rate of neonates, who deaths had come to constitute the bulk of infant mortality in the developed nations. That effort resulted in the perfection of diagnostic techniques and drugs that have proven effective in regulating pregnancy and preventing premature labor, and in the development of sophisticated surgical, therapeutic, and intensive care techniques and technologies to correct congenital deformities and to counter the risks faced by low birth-weight and premature babies. It also resulted in significant improvements in both the quality and availability of nutritional, prenatal, and natal care. As a consequence of a century of profound decline in infant mortality, babies born in the late twentieth century in developed nations enjoyed a probability of surviving their first year unimaginable through most of human history.
Twentieth-Century Infant Mortality in Less Developed Nations
As the second half of the twentieth century began, life expectancy in the less developed nations of the world was not much better than it had been for centuries, largely because infant mortality remained astronomical. Some areas, of course, were less inimical to infant life than others. In Latin America less than 13 percent of all infants born died each year, while in Asia over 18 percent did. Worst off was Africa, particularly sub-Saharan Africa, where infant mortality ranged above 20 percent. Indeed, in some sub-Saharan countries, over a third of all children born perished before they reached five years of age.
Over the next half century, infant mortality dropped dramatically in all these regions, though at different times and rates. In Asia, particularly China, it dropped earliest and fastest, declining from over 19 percent at mid-century to around 4 percent three decades later. Infant mortality also dropped significantly and relatively quickly in Latin America,
halving by the mid-1980s. Even Africa, which remains the continent most dangerous to infant life, ultimately achieved over a 50 percent decline in the infant death rate. Indeed, at eighty-seven infant deaths per thousand births, the 2000 African infant mortality rate is lower than that in the United States on the eve of World War I.
Contributing significantly to this drop in infant mortality during the second half of the century has been an international movement to improve child health and survival that has been led primarily by two organizations created in the aftermath of World War II: the United Nations Children's Fund (UNICEF) and the World Health Organization (WHO). Through the 1970s, this international effort involved both specific medical and public health interventions aimed at improving nutrition, controlling the incidence of malaria, increasing the availability of immunizations, and promoting in poorer countries the development of health care and public health systems emulating those of wealthier countries. While efforts to purify water supplies generally had positive effects, the overall results of the effort were mixed, and in the early 1980s UNICEF and WHO embarked on a new community-based child survival program which sought to increase immunization and educate community members about proper sanitation, prenatal hygiene, breast-feeding, and the use of a newly developed and simple oral rehydration salt formula for treating infants with acute diarrhea. In combination with continuing efforts to make clean water available, this community-based program seems to have had considerable success. Between the mid-1980s and 2000, infant mortality throughout the world dropped by approximately 30 percent.
Not all infants, of course, have benefited equally from this drop in infant mortality in the less-developed regions. There is considerable variation not only between regions but
also between different nations in the same region. In sub-Saharan Africa, which each year accounts for over 40 percent of the world's deaths of children less than five, infant mortality in the year 2000 ranged from a low of 58.8 per thousand in Kenya to a high of 130.5 in Malawi. Similarly, in western Asia, Iran had an infant mortality rate of 28.1 while neighboring Afghanistan suffered a rate of 137.5, the highest in the world. Even in the Americas, tremendous variation still exists. Only a relatively narrow stretch of water separates Cuba from Haiti, but an immense gulf exists between their infant mortality rates. In 2000 Cuba had a rate of 7.7 while Haiti had one of 96.3.
As in the past, the causes of infant mortality remain numerous and many: the communicable childhood diseases, diarrheal diseases and gastroenteritis from poor sanitation, pneumonia and other respiratory diseases, an environment infested with the parasites that cause malaria and other debilitating diseases, and the triangle of poverty, malnutrition, and lack of medical supervision that adversely affects the health of pregnant women and leads to gestational problems. Unlike the past, however, relatively effective means of dealing with these causes now exist. The incidence and deadliness of many of the communicable infectious diseases can be controlled by immunization and the use of antibiotics; the incidence of diarrhea and gastritis by improved sanitation, clean water, and use of rehydration therapies; and the incidence of gestational complications by prenatal care programs. All these, however, require resources and the willingness to use them. So long as some countries remain wretchedly impoverished and have governments which cannot or will not apply national resources to saving infants, the modern transformation of infancy from a period characterized by nothing so much as precariousness to one in which survival is almost a certainty will remain incomplete.
See also: Contagious Diseases; Fertility Rates; Obstetrics and Midwifery.
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U.S. Census International Database. 2000. Available from <www.census.gov>.
Infant mortality refers to deaths of children under the age of one year. It is measured by the infant mortality rate, which is the total number of deaths to children under the age of one year for every 1,000 live births. The infant mortality rate is often broken down into two components relating to timing of death: neonatal and postneonatal. The neonatal mortality rate refers to the number of deaths to babies within 28 days after birth (per 1,000 live births). Sometimes a special type of neonatal mortality is assessed. The perinatal mortality rate measures the number of late fetal deaths (at or after 28 weeks gestation) and deaths within the first 7 days after birth per 1,000 live births. The postneonatal mortality rate involves the number of deaths to babies from 28 days to the end of the first year per 1,000 live births. The distinction between neonatal (and perinatal) and postneonatal mortality is important because the risk of death is higher close to the delivery date, and the causes of death near the time of birth/delivery are quite different from those later in infancy. Therefore, effective interventions to reduce infant mortality need to take into account the distribution of ages at death of infants.
Many developing countries lack the resources to keep track of infant deaths; therefore data for these areas are estimates only. Another methodological problem in measuring infant mortality is ascertaining the number of live births. Sometimes this problem is one of undercounts of births (i.e., births are not registered and thus not counted); sometimes the difficulty lies in inconsistently differentiating stillbirths and live births, especially across countries because this distinction is not as clear-cut as one might imagine.
Infant Mortality in International Perspective
Table 1 provides infant mortality rates for the world, for developed and developing countries, and by continent, with some selected countries that highlight the range of levels. At 57, the world's infant mortality rate has never been lower; however, differences across the world are substantial. Africa's rate (88) is ten times higher than the average rate (8) for the developed countries. Within Africa the highest levels of infant mortality in the world are experienced, with rates as high as 157 in Sierra Leone. On average the rate for Asia (56) is somewhat lower than for Africa, but some Asian countries such as Afghanistan have rates (150) as high as anywhere in the world. On the other hand, Hong Kong's rate (3.2) is very low, illustrating that the most variation in infant mortality level occurs in Asia. Both Europe and North America (the United States and Canada) have low levels of infant mortality, with average rates well under 10. However, European variation is not inconsequential; rates in at least some parts of Eastern Europe are nearly 10 times higher than in northern European countries such as Iceland and Sweden.
Overall, income and education, both at the societal and individual levels, are closely associated with infant mortality. While the relationship between infant mortality and level of socioeconomic development is not perfect, the infant mortality rate is commonly used more than any other measure as a general indicator of socioeconomic wellbeing and of general medical and public health
|Infant mortality rates by region (and selected countries), 2001|
|Less Developed Countries||63|
|Latin America (and the Caribbean)||35|
|North America (U.S. and Canada)||7|
|SOURCE : Population Reference Bureau. 2001 World Population Data Sheet. Washington, DC: Population Reference Bureau, 2001.|
conditions in a country. Richer countries can provide the basic ingredients for infant survival: clean water, sanitary surroundings, adequate food and shelter, and access to health care services. A large portion of infant mortality is due to infectious and communicable diseases, which sanitary practices and an adequate diet do much to prevent.
At the individual level mothers (and fathers) with higher income and education are more likely to possess knowledge of sanitary behaviors and the money for adequate food, as well as to take their babies to a health service if needed. Especially important in the latter regard is oral rehydration therapy, which is effective in saving babies from dying from the dehydration that accompanies diarrhea.
Causes of Infant Deaths
Postneonatal mortality is most often caused by infectious diseases, such as pneumonia, tetanus, and malaria. An important factor in reducing post-neonatal mortality is adequate nutrition, particularly breast milk, which provides babies with both the nourishment and the antibodies to fight infectious diseases. Of course adequate breast milk depends upon adequately nourished mothers. Also important is the proper use of breast milk substitutes—mixing formula with unclean water and/or diluting formula for cost-savings reasons, both known to occur in developing countries, have negative affects on the health of infants. The promotion by multinational corporations of breast milk substitutes to women in poorer countries has been one of the travesties of our times; it is estimated that 1.5 million deaths a year could be prevented by breast-feeding.
The issue of HIV-infected mothers' breast-feeding has become controversial. A number of countries have instituted policies that recommend that mothers with HIV (human immunodeficiency virus) not breast-feed, based on some evidence of mother-to-child transmission of HIV through breast-feeding. In contrast are policies that promote breast-feeding in areas with high HIV prevalence. Because breast-feeding protects against the infectious diseases that take the lives of millions of infants every year, there is policy debate about the best course of action. Researchers do not know if the protection against infectious diseases afforded by breast-feeding outweighs the risks of HIV transmission to children, so it is not possible to make a definitive conclusion about the risks and benefits of breast-feeding by mothers with HIV. However, a 2000 study by the World Health Organization (WHO) Collaborative Study Team on the Role of Breastfeeding on the Prevention of Infant Mortality determined that the breast-fed babies of mothers with HIV had six times the protection against diarrheal deaths in the first few months of life than babies not breast-fed. In the second half-year of life, protection against both diarrheal and acute respiratory infections was about double that for non-breast-fed babies. Protection declined with age of child, and was greatest for the children of the least educated women. It appears the benefits may out-weigh the risks for limited (in time) breast-feeding and for poorer women, who are unable to afford safe substitute milk substitutes. However, another issue to consider is that breast-feeding may negatively affect the health of mothers with HIV/AIDS (human immunodeficiency virus/acquired immunodeficiency syndrome).
Another cause of infant mortality is violence. Research conducted in two areas in India show that wife beating, closely linked with patriarchal social structures, leads to both pregnancy loss and infant mortality. Other violence, such as infanticide, the deliberate killing of infants, is extremely difficult to document, but it seems likely that some portion of the "missing girls" in India and China were the victims of infanticide. When infanticide is practiced, it is most likely a response to difficult economic circumstances (and coercive population policy, in the case of China) in conjunction with male-child preference.
Violence against babies is not limited to developing countries. Violence to infants in the form of head trauma, including shaken baby syndrome (SBS), has been studied in America. In 2000 the researchers Suzanne Starling and James Holden found that in both a western and southern U.S. sample men are more likely (70 percent) to be perpetrators of violence, with biological fathers (not necessarily married to the mother or living with the child) the most likely to cause fatal (and nonfatal) head trauma to infants, followed by boyfriends. The victims were more likely to be boys, with an average age of six months.
Excluding violence, neonatal mortality (in contrast to postneonatal mortality) is less likely to be the direct result of social, economic, and environmental conditions. Major causes of neonatal mortality include low birthweight, preterm (premature) birth, congenital malformations, and sudden infant death syndrome (SIDS). In developed countries most infant mortality is concentrated in the early neonatal period, with the aforementioned causes of death predominant.
Infant Mortality in the United States
Over the course of the twentieth century, each developed country has a somewhat unique trend in the timing and tempo of infant mortality decline, an examination of the American case provides a general sense of the Western pattern. In the early part of the twentieth century, the infant mortality rate was in excess of 100—much higher than in the developing countries (on average) of the twenty-first century. In other words, more than 10 percent of children born died in the first year of life. In the earlier stage of decline, postneonatal mortality was reduced. Over the period from 1915 to around the end of World War II, postneonatal mortality experienced a steady and dramatic decline to a level of approximately 10 (Wegman 2001). At the same time, deaths of babies from 28 days to one year of age decreased as a proportion of total infant deaths (i.e., all death under the age of one). This decline was due to improvements in nutrition and in public health, such as clean drinking water, sewage disposal, and personal hygiene. Deaths due to diarrhea and infectious diseases such as pneumonia, diphtheria, and typhoid fever were reduced dramatically. In the post–World War II era, vaccines and other medical interventions such as antibiotics played a role in further declines.
Neonatal mortality declined more slowly and later than postneonatal mortality. It was not until around 1975 that the neonatal rate reached 10—lagging behind neonatal mortality by a generation. Neonatal mortality decline is much less dependent on nutrition and public health measures; rather, it requires more sophisticated medical interventions, especially to keep low birthweight babies alive. In the twenty-first century, approximately two-thirds of all infant deaths occur in the neonatal period, with the leading causes of death associated with low birthweight, congenital malformations, and SIDS.
The latest data available reveal that the United States' rate for infant mortality is not as low as one might expect. According to the Population Reference Bureau, its rate of 7 is surpassed by several European countries (Denmark, Iceland, Finland, Germany, Netherlands, Switzerland, and the Czech Republic all have rates under 5), several Asian countries (Singapore, Hong Kong and Japan all have rates under 4), Canada (5.5), Australia (5.3), and New Zealand (5.5) (Wegman 2001). Countries in the 7 to 8 range in infant mortality, along with the United States, include Cyprus, Malaysia, and Cuba—all considerably less developed than the United States. The United States' comparatively poor ranking in infant mortality has led to concern at the national level, especially relating to racial inequalities. The figures for African Americans show a consistent disadvantage in infant mortality, a disadvantage that is increasing, especially with regard to neonatal mortality.
An important factor influencing the relationship between race and infant mortality is birth-weight. At the end of the twentieth century, 13 percent of (non-Hispanic) African-American babies were born in the low birthweight category (under 2,500 grams or approximately 5 pounds), compared with approximately 6.5 percent of (non-Hispanic) Caucasian babies and Hispanic infants. The reasons why African-American women are so much more likely to give birth to high-risk, low birthweight infants remain unclear, although differences in prenatal care may be implicated, as may the absence of a national health care system and inadequate social welfare. Another factor to note is that the infant mortality of whites is lowered by the contribution of immigrants who have lower infant mortality than the native born.
In the decade of the 1990s, Caucasian women (and American Indian and Asian/Pacific Islander women) experienced some increase in low birth-weight babies. This statistic has been attributed in part to an increase in multiple births (e.g., twins, triplets), which are more likely to be low birth-weight newborns. Increases in multiple births are associated with fertility drugs and reproductive technologies such as in vitro fertilization and, to some degree, later age at childbearing. This increase in low birthweight infants does not bode well for future declines in neonatal mortality.
In developing countries considerable progress against infant mortality, especially postneonatal mortality, can be accomplished through the implementation of basic public health measures that will reduce infant deaths due to diarrhea and infectious disease. However, the HIV/AIDS epidemic places some countries, especially sub-Saharan Africa and parts of Southeast Asia, in a difficult position since HIV/AIDS kills infants directly and, through lowering immune functioning, indirectly. In developed countries, the major immediate challenge is to reduce the proportion of low birthweight infants. While improved prenatal care will advance that goal, restructuring (i.e., dismantling) of welfare states presents a possible barrier, as does the continuing popularity of technologies to increase fertility. Another unknown factor in all countries is the future role of re-emerging old and emerging new viruses and pathogenic bacteria; these microbes could significantly increase postneonatal mortality.
See also: Causes of Death; Gender and Death; Infanticide
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ELLEN M. GEE
Infant mortality is defined as the death of an infant between birth and one year of age. Sociologists often look at a nation's infant mortality rate to determine that particular nation's general state of health. International statistics show that the world's industrialized nations have a lower infant mortality rate than that of poorer nations. Infant death may result from a number of causes—stemming from congenital and environmental factors as well as poor diet and medical care—but premature birth is among the most common.
A careful look at individual nations with lower rates often reveals a distinct difference among that nation's ethnic groups; wealthy white babies have a much lower mortality rate than do poor blacks, for instance. Poor mothers have less access to health care and thus have more premature babies, who are then at a higher risk of disease and death. It is every country's goal to improve its infant mortality rates so that every baby born has an equal chance of survival.
Among the countries of the world, the less industrialized nations have high infant mortality rates of about 100 per 1000 births. Western countries that provide good health care programs have lower rates, between 4 to 15 per 1000 births. Japan leads the world with the lowest infant mortality rate of 4 per 1000; Canada and Italy follow with 6 per 1000. In the United States, the rate is about 8.4 per 1000. Poor nations in Asia and Africa have appallingly high rates. For example, Afghanistan's is 147 per 1000, and Sierra Leone's is 133 per 1000. An interesting exception is the impoverished country of Cuba, which has a good infant mortality rate of 9.4 per 1000.
Within Western nations, the rates of infant mortality vary considerably. Different factors explain these rates: economic status and education are among the most important. Women who receive little or no prenatal care are at greater risk of complications during their pregnancies—both to themselves and to their babies. These women have a higher maternal death rate, and their babies have a higher infant mortality rate than mothers who receive adequate medical care during their pregnancies. If the baby does survive, there is more risk of its being premature and/or seriously sick.
A troubling gap exists between black and white infant mortality rates. Even black women who receive prenatal medical care have more premature babies and more low birth weight babies. The black infant mortality rate has been consistently higher than that of whites. Rates for both ethnic groups have declined since 1950, but the rate of white babies has declined almost twice as quickly as that for black babies. In 1950 the infant mortality rate was about 30 per 1000 for white babies, and 50 per 1000 for black babies. Though the figures for both blacks and whites declined dramatically to 15.7 for blacks and 7.4 for whites by 1991, the gap between the two groups had actually widened since 1950 and is not expected to decrease before the year 2010.
A major reason for the drop in infant mortality in recent years is better prenatal care. One part of this care is the use of fetal monitors during pregnancy and labor. Ultrasound helps the physician measure the size and growth of the fetus, and to determine if a problem exists, such as placenta previa, which might necessitate delivery by cesarean section. Monitors also can predict how the fetus will react during labor and if it can survive the stress of a natural delivery. During labor itself, an electrode can be attached to the baby's scalp; if the infant appears to be in distress, the doctor may decide to perform an immediate cesarean section.
The causes of infant mortality are several, such as certain congenital problems, premature babies and their low birth weights, and sudden infant death syndrome (SIDS). Researchers discovered that babies who sleep on their backs are much less likely to die from SIDS, with the result that the rate of SIDS has dropped by almost 40 percent by 1996. Of all the causes, however, premature births remain the major cause of infant mortality.
The number of premature babies has increased with the higher number of multiple births, which are caused by popular fertility treatments. If a baby is born before 37 weeks of gestation, it is known as a premature baby or a "preemie." These babies have not reached their full birth weight and can weigh as little as 800 grams or about two pounds. A female fetus matures more quickly than a male, so if a premature baby is a girl, she has a better chance of survival than a boy. All preemies have serious problems because their tiny organs are not fully developed. Premature infants need the special care provided by a neonatal intensive care unit where the baby is kept warm, fed, and protected in the proper environment.
An important part of the neonatal intensive care unit (NICU) is the incubator, a special bed or chamber that is kept at a constant temperature of 31° to 32° C (88° to 90° F). This is vital for premature babies because they lack sufficient body fat to keep warm. Incubators have been used since the latter part of the nineteenth century and helped premature babies survive. Today, neonatal intensive care units use both incubators and radiant warmers. Incubators are made of clear plastic and completely enclose the newborn infant, maintaining a certain temperature and level of humidity. A radiant warmer also keeps the baby warm but is completely open on top so that specialists can have easy access to the baby.
Despite the efforts of the neonatal specialists, the tiny baby still faces many health problems. The infant can develop jaundice and have serious respiratory problems. Jaundice causes the skin and eyes to be yellow; it is a common and easily treatable condition resulting from high levels of bilirubin. The premature baby's liver is not yet able to process the bilirubin, so it accumulates in the blood. If the levels are too high, the baby can suffer brain damage. Therefore, the neonatal staff closely monitors a premature baby's bilirubin levels and places the baby under special lighting to help eliminate the bilirubin. In an extreme case of jaundice, the baby may need a blood transfusion.
The most serious problem of the premature infant is breathing. The baby's lungs require a chemical, called surfactant, to function properly. If a premature infant, however, does not have sufficient surfactant in its lungs, the baby develops respiratory distress syndrome. Doctors try to measure the baby's level of surfactant even before it is born.
A test can be performed on the expectant mother if the doctor suspects a premature delivery. This test, an amniocentesis, will determine the level of surfactant in the lungs of the fetus. In an amniocentesis, a needle is injected through the mother's abdomen into the uterus; a sample of the amniotic fluid is taken and checked for surfactant. If the level is low, the doctor will inject the mother with a corticosteroid, which works in about 24 hours.
If the premature baby with respiratory distress syndrome is about to be born, however, there is no time for the injection. After the birth, the infant is placed in the neonatal intensive care unit, and a mechanical ventilator helps the baby breathe. The ventilator, or inhaler, administers the artificial surfactant and helps the baby's tiny lungs function more normally. The nurses continue to monitor the baby's levels of oxygen and carbon dioxide.
Before the NICU was developed in the 1960s, premature babies were treated with an excessive amount of oxygen to help their under-developed lungs. The result is now thought to have caused blindness by making the baby's retina become loosened. Medical researchers agree, however, that oxygen levels only partially explain the damage to the eyes of a premature infant. Babies in the NICU are given regular eye exams to monitor the blood vessels in their eyes. Doctors have turned to laser surgery on preemies in an effort to prevent detached retinas.
Until the late 1960s, hyaline membrane disease was another respiratory problem that was a major cause of death in premature babies. Doctors found that using artificial surfactant helped the infant's tiny lungs function more properly. The last two decades of the twentieth century saw the life expectancy of premature babies increase dramatically, due mainly to the use of surfactant and the NICU. Nevertheless, respiratory distress syndrome remains the major problem for babies born before the 28th week or weighing three pounds or less.
Various factors are responsible for premature delivery. The mother's lifestyle, for example, can definitely affect when her baby is born; smoking, drinking, and a poor diet can all cause her to go into labor early. In addition, there are also physical reasons for premature delivery, such as a mother's illness, infection, or a uterine abnormality. Access to prenatal medical care is also important.
Medical research and the development of the neonatal intensive care unit have allowed more premature infants to survive, but doctors have not yet discovered conclusively how to prevent babies from being born too small or too early. Many babies, about one-tenth of all babies born in the United States, have either a low birth weight or are pre-term. Researchers do know that smoking among pregnant women causes 20 percent of low birth weight babies, a factor that could be prevented. However, they have not yet determined how to prevent the other 80 percent of small babies being born or the specific causes of pre-term births.
The disturbing fact remains that African-American infants are twice as likely to be either pre-term or of low birth weight than either Asian-American or white babies. Until society addresses this discrepancy, the United States will continue to rank far behind many other countries in infant mortality.
M. E. ELGHOBASHI
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Oakley, Ann. The Captured Womb: A History of the Medical Care of Pregnant Women. New York: Blackwell, 1984.
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Singh, Gopal K., and Stella M. Yu. "Infant Mortality in the United States: Trends, Differentials, and Projections 1950 through 2010." The American Journal of Public Health 85, No. 7 (July 1995): 957-64.
The infant mortality rate is the number of deaths of infants under one year of age per 1,000 live births in a given population. In 2002, the United States' infant mortality rate varied widely by race of the mother from 14.3 for infants of black mothers to 5.9 for infants of Hispanic mothers to 5.8 for infants of white mothers. As can be noted, the mortality rate for black infants is more than twice that of white infants. The overall infant mortality rate in 2002 for all races was 7.0 per 1,000 live births, which was a slight increase over the previous year.
Infant mortality rate is one of the key indicators of a nation's health status. When the rate increases, as it did from 2001 to 2002, the factors that precipitated this change need to be assessed and scrutinized. The U.S. infant mortality rate is of great concern because the United States has fallen to the twenty-second nd place among industrialized nations in infant mortality rankings. Therefore, healthcare professionals and the public have stressed the need for better prenatal care, coordination of health services, and the provision of comprehensive maternal-child services.
Infant mortality rates have typically been the highest for the babies of adolescent mothers and lowest for women in their late 20s and early 30s. The rates have also been high for women in their forties and older. In general, infant mortality rates decrease with increasing maternal educational levels. Similarly the infant mortality rate for unmarried mothers is often more than 83 percent higher than the mortality rate for married women. Likewise, the infant mortality rate is characteristically higher for the infants of mothers who smoke than for those of nonsmokers.
The leading cause of infant mortality is congenital malformations, deformations and chromosomal abnormalities with a rate of 20.2 percent. Disorders related to short gestation and low birth weight was the second leading cause of death for all infants at 16.4 percent of all deaths. Sudden infant death syndrome (SIDS) is the third leading cause of infant death. Its incidence decreased by about 9 percent, which it has been doing since 1988. The fourth leading cause of death comes under the heading of newborn affected by maternal complications of pregnancy. This rate actually increased from 2001 to 2002 from 37.2 per 100,000 live births to 42.9 per 100,000 in 2002.
An analysis of the data established that the rise in the infant mortality rate was concentrated in the neonatal period (less than 28 days) and primarily in the first week of life where more than half of all infants' deaths occur. Final birth data for 2002 made it apparent that two key predictors of infant health, the percentage of infants born preterm (less than 37 weeks gestation) and low birth weight (less than 2,500 grams) rose during this time frame. This has been a continuing long-term upward trend. The cesarean section rate for 2002 rose to 26.1, which is the highest ever recorded in the US. The primary cesarean rate was 7 percent higher than the previous year, and the rate of vaginal birth after cesarean (VBAC) experienced a sharp decline. The cesarean rate increase could be due to nonmedical factors as demographics, physician practice patterns, and maternal choice. Other contributing factors may be the use of continuous electronic fetal monitoring and inductions before 41 weeks gestation. Unnecessary interventions can contribute to a rise in cesarean rates. On the other hand, the perinatal mortality rate (the number of late fetal deaths [28 weeks or more gestation] and early neonatal deaths [less than 7 days] per 1,000 live births) remain unchanged.
The infant mortality rate increased in the United States in 2002 for the first time since 1958, which indicates a need to examine what factors contributed to this raise. Is there a difference in mortality rates among racial groups? That is obvious—the rate for blacks is 14.2 and the rate for whites is 5.8. Experts associate this difference with the availability of prenatal care to minorities. It is expensive, and over 40 million Americans do not have health insurance. The mother's socioeconomic status is a possible contributing factor because the leading cause of death was related to congenital malformations, which in some cases can be eliminated with appropriate nutritional intake and prenatal vitamins . Lack of prenatal care could also contribute to the fourth largest cause of infant death, which is maternal complications. Many other industrialized countries have a socialized system of health care, which offers universal access to prenatal care and helps lower country-wide infant mortality rates.
Recent data showed good news for parents of teenagers. The teen birth rate declined by 30 percent over the past decade to a historic low and the rate for black teens was down by more than 40 percent. For young black teens (15 to 17 years) the results were even more striking—the rate was cut in half since 1991. The average age at first birth was 25.1 years in 2002, an all-time high in the United States. Birth rates for women 35–39 (41 births per 1,000 women) and 40–44 (eight per 1,000) were the highest in more than three decades. The rate for women ages 20–24 (104 births per 1,000 women) was on the decline and the rate for those 25–29 was stable, but still the highest of all age groups, at 114 per 1,000 women. In contrast, the rate for teens was 43 per 1,000. In addition, just over one in 10 women smoked during pregnancy in 2002, a decline of 42 percent since 1989.
Perinatal mortality —The number of late fetal deaths, 28 weeks or more gestation, and neonatal deaths that occur in the first seven days.
Center of Disease Control and Prevention; 1600 Clifton Rd.; Atlanta, GA 30333.(800)311-3435. Web site: <www.cdc.gov>.
U.S. Department of Health and Human Services. National Center for Health Statistics. Hyattsville, MD 20782. (301) 458-4000.
Centers for Disease Control. Infant Mortality: Fast Stats. [cited March 6, 2005]. Available online at: <http://www.cdc.gov/nchs/fastasts/infmort.htm>.
Child Trends Databank. Infant, Child, and Youth Mortality. [cited March 6, 2005]. Available online at: <http://www.childtrendsdatabank.org/indicators/63ChildMortality.cfm>.
Linda K. Bennington, MSN, CNS
Infant mortality is defined as the death of a live-born infant within the first year of life. As an indicator of a nation's health status, infant mortality can serve as a reflection of a society's available resources and technology (including social distribution, access, and use), the status of women in society, and the health care provided to the most vulnerable segments of the population. Common causes of infant death include birth defects, complications related to prematurity, sudden infant death syndrome (SIDS), and respiratory distress syndrome. In 1996 these accounted for more than half of all infant deaths in the United States. Other causes include maternal and placental complications, infections, and unintentional injuries.
While the yearly infant mortality rate (the annual number of infant deaths/annual number of live-born infants per thousand) in the United States has been declining steadily from 100 in 1915 to 7.2 in 1998, its ranking among other developed countries continues to worsen, leaving the United States ranked behind most Western European countries. This poor ranking internationally can be attributed in part to global variations in live birth definitions and recording practices, but it also reflects racial and ethnic disparities in health status, access to health care, and socioeconomic conditions.
See also:BIRTH DEFECTS; BIRTHWEIGHT; PREMATURE INFANTS; PRENATAL CARE
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