Chapter 1
Defining Health and Wellness

Individual health is closely linked to community health—the health of the community in which individuals live, work, and play. Likewise, community health is profoundly affected by the collective beliefs, attitudes, and behaviors of everyone who lives in the community.

—Healthy People 2010: Understanding and Improving Health, U.S. Department of Health and Human Services, 2000

Many definitions of health exist. Most definitions consider health as an outcome—the result of actions to produce it, such as good nutrition, immunization to prevent disease, or medical treatment to cure disease. The American Heritage Dictionary defines health as fixed and measurable—"the overall condition of an organism at a given time." However, health also may be viewed as the active process used by individuals and communities to adapt to ever-changing environments.

The eleventh edition of Merriam-Webster's Collegiate Dictionary defines health as "the condition of being sound in body, mind, or spirit; especially: freedom from physical disease or pain." In 1948, however, the Constitution of the World Health Organization (WHO) defined health as "a state of complete physical, mental, and social well-being and not merely the absence of disease and infirmity." This still widely used definition is broader and more positive than simply defining health as the absence of illness or disability.

Expanding on the WHO definition of health and the commonly understood idea of well-being, the concept of wellness has been defined by the National Wellness Association as "an active process of becoming aware of and making choices toward a more successful existence." Wellness encompasses how people feel about various aspects of their lives. Six interrelated aspects of human life are commonly known to comprise wellness:

• Emotional wellness refers to awareness, sensitivity, and acceptance of feelings and the ability to successfully express and manage one's feelings. Emotional wellness enables people to cope with stress, maintain satisfying relationships with family and friends, and assume responsibility for their actions.
• Intellectual wellness emphasizes knowledge, learning, creativity, problem solving, and lifelong interest in learning and new ideas.
• Occupational wellness relates to preparing for and pursuing work that is meaningful, satisfying, and consistent with one's interests, aptitudes, and personal beliefs.
• Physical wellness is more than simply freedom from disease. The physical dimension of wellness concentrates on prevention of illness and encourages exercise, healthy diet, and knowledgeable, appropriate use of the health care system. Physical wellness requires individuals to take personal responsibility for actions and choices that affect their health. Examples of healthy choices include wearing a seatbelt in automobiles, wearing a helmet when bicycling, and avoiding tobacco and illegal drugs.
• Social wellness is acting in harmony with nature, family, and others in the community. The pursuit of social wellness may involve actions to protect or preserve the environment or contribute to the health and well-being of the community by performing volunteer work.
• Spiritual wellness involves finding meaning in life and acting purposefully in a manner that is consistent with one's deeply held values and beliefs.

The concept of wellness is broader and includes more facets of human life than the traditional definition of health, and the two differ in an important way. When defined as the absence of disease, health may be measured and assessed objectively. For example, a physical examination and the results of laboratory testing enable a physician to determine that a patient is free of disease and thereby healthy.

In comparison, wellness is a more subjective quality and is more difficult to measure. The determination of wellness relies on self-assessment and self-report. Further, it is not necessarily essential that individuals satisfy the traditional definition of good health to rate themselves high in terms of wellness. For instance, many people with chronic (ongoing or long-term) conditions—such as diabetes, heart disease, or asthma—or disabilities report high levels of satisfaction with each of the six dimensions of wellness. Similarly, people in apparently good health may not necessarily give themselves high scores in all six aspects of wellness.

THE HEALTH OF THE UNITED STATES

A primary indicator of the well-being of a nation is the health of its people. Many factors can affect a person's health: heredity, race/ethnicity, gender, income, education, geography, exposure to violent crime, exposure to environmental agents, exposure to infectious diseases, and access to and availability of health care.

Whereas physicians and other health practitioners observe the influences of these factors as they care for individual patients, epidemiologists (public health researchers who study the occurrence of disease in populations) examine the distribution and rates of diseases and injuries in the population. The practitioner and epidemiologist each apply the scientific method to achieve their objectives, but they use it in varying ways. For instance, in the "database" step of the scientific method, the practitioner uses history and physical examination to determine a patient's health; the epidemiologist uses surveillance and description. The practitioner seeks to deliver appropriate treatment to individual patients; the epidemiologist recommends actions to prevent the spread of disease or otherwise improve the health of an entire community or population.

Epidemiologists and other public health professionals assess health by determining the incidence and prevalence rates of disease and disability in a given community. Incidence is a measure of the rate at which people without a disease develop the disease during a specific time period, and it describes the continuing occurrence of disease over time. For example, a researcher might report that men in a given community age sixty-five and older have a 2% incidence of heart disease. Prevalence describes a group or population at a specific point in time. For example, the prevalence of high blood pressure found during screening at a health fair on a specific day might be 22%.

Other measures of the health of a population, such as natality (birth) and mortality (death) rates, are known as vital health statistics. This chapter provides an overview of vital health statistics and the health status of Americans.

BIRTHRATES AND FERTILITY RATES

The birthrate is the number of live births per one thousand women. The fertility rate, however, is the number of live births per one thousand women between fifteen and forty-four years of age, generally considered a woman's prime childbearing years.

In Health, United States, 2005 (2005, http://www.cdc.gov/nchs/data/hus/hus05.pdf), the National Center for Health Statistics (NCHS) reported that there were more than four million live births (4,089,950) in the United States in 2003, which basically did not change from 2002. This number translated to a birthrate of 14.1 births per one thousand women—among the lowest rates recorded for the United States and comparable to the U.S. birthrate in 1999. (See Table 1.1.) Between the most recent high point, 16.7 in 1990, and the most recent low point, 13.9 in 2002, the crude birthrate declined 16.8%. Although the NCHS reports that the number of live births has increased steadily since 1970, the birthrate and fertility rate have remained relatively stable since 1999.

Birthrates have continued to decline for teenagers ages fifteen to nineteen. In 2003 the number of live births per one thousand teens ages fifteen to seventeen was 22.4, down from the last most recent peak of 37.5 in 1990, a decrease of 40.3%. The number of live births per one thousand young women ages eighteen to nineteen in 2003 was 70.7, down from 88.6 in 1990, a decrease of 20.2%. (See Table 1.1.)

In contrast, the birthrates for women ages twenty-five to forty-four increased in 2003. The birthrates for women ages thirty-five to thirty-nine, which has been increasing dramatically since 1980, increased by another 5.8% in 2003—43.8 births per one thousand women (up from 41.4 births per one thousand women in 2002). (See Table 1.1.) The birthrate for this age group increased by more than 38% between 1990 and 2003, with an average increase of about 3% per year.

Women ages twenty to twenty-nine continued to have the highest birthrates, although the proportion of births to these women has declined in recent years.

Fertility rates focus on live births to mothers in the primary childbearing age group, fifteen to forty-four. In 2003 the fertility rate for American women was 66.1 births per one thousand women, which is a slight increase from 2002 (64.8) but a decline of 6.8% from 1990 (70.9). Total fertility rates, which offer an index of lifetime fertility among women, not only varied by age but also by race and ethnic origin. In 2003 the fertility rate for Hispanic women (96.9 births per one thousand Hispanic women ages fifteen to forty-four) was two-thirds (65.6%) higher than for non-Hispanic white women (58.5 births per one thousand). (See Table 1.1.)

Factors other than age, race, and ethnicity can have dramatic effects on fertility and birthrates. For example, although women who are currently married and living with their husbands have much higher fertility rates than those women who have never married or are separated, widowed, or divorced, the NCHS in Health, United States, 2005 reports that in 2003 the birthrate for unmarried women has been increasing steadily over the years, to nearly forty-five births per one thousand unmarried women ages fourteen to forty-four. This increase has occurred in spite of the decrease in the birthrate among

teenagers. The Centers for Disease Control and Prevention (CDC) cites successful health prevention programs that include education emphasizing prevention of pregnancy through abstinence (avoiding sexual contact) and contraception (measures to prevent pregnancy) as one factor that has contributed to the decline in teen birthrates along with a leveling-off of sexual activity among teens.

Prenatal Care, Prematurity, and Low Birth Weight

Early prenatal care, defined as pregnancy-related care started in the first trimester (one to three months), can detect and often correct many potential health problems early in pregnancy. Regular visits to a physician or clinic usually give the mother-to-be information and encouragement about eating properly, exercising regularly, taking prenatal vitamins, and avoiding harmful substances such as alcohol, drugs, and tobacco. The benefits of these preventive measures can make literally a lifetime of difference for a newborn.

Sophisticated diagnostic medical procedures, such as obstetric ultrasound scans and amniocentesis, can be performed to detect possible birth defects and other prenatal problems. Ultrasound uses high-frequency sound waves to compose a picture of the fetus and is used to detect and assess fetal development and malformations in the fetus. During amniocentesis, a physician inserts a needle through the abdominal wall into the uterus to obtain a small sample of the amniotic fluid surrounding the fetus. When tested in a laboratory, this fluid can reveal chromosomal abnormalities, metabolic disorders, and physical abnormalities.

Pregnant women older than age thirty-five are generally advised to undergo amniocentesis and other diagnostic testing, because they are at greater risk than younger women of giving birth to babies with chromosomal abnormalities such as Down syndrome (also called Down's syndrome). Instead of the normal forty-six chromosomes, newborns with Down syndrome have an extra copy of chromosome twenty-one, giving them a total of forty-seven chromosomes. These children have varying degrees of mental retardation, and, according to the Cincinnati Children's Hospital Medical Center (http://www.cincinnatichildrens.org/health/heart-encyclopedia/disease/syndrome/down.htm), up to 50% have congenital heart diseases. The center notes that the incidence of Down syndrome is one in every seven hundred to eight hundred live births. And, according to a January 6, 2006, report by the CDC ("Improved National Prevalence Estimates for 18 Selected Major Birth Defects—United States, 1999–2001," http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5451a2.htm), the average prevalence of children born with Down syndrome in an eleven-state study was 12.9 per ten thousand live births.

Ideally, every woman should receive prenatal care, and according to the NCHS, the United States is capable of delivering prenatal care to nearly all pregnant women during the first trimester of pregnancy. Not all mothers-to-be, however, seek or receive early or adequate prenatal care. Adequate/adequate plus prenatal care is defined as pregnancy-related care beginning in the first four months of pregnancy with the appropriate number of visits for gestational age, according to the Adequacy of Prenatal Care Utilization Index. According to the March of Dimes Birth Defects Foundation, a national voluntary organization that seeks to improve infant health by preventing birth defects, in 2002 nearly 75% of expectant mothers received adequate/adequate plus prenatal care, while 14% received intermediate care (less than optimal but not inadequate) and almost 12% received inadequate care (http://www.marchofdimes.com/peristats/level1.aspx?reg=99&top=5&stop=33&lev=1&slev=1&obj=3).

The percentage of expectant mothers receiving prenatal care beginning in the first trimester steadily increased from 68% in 1970 to 84.1% in 2003. (See Table 1.2.) More white (85.7%) and Asian or Pacific Islander (85.4%) women received early prenatal care than did Hispanic or Latino (77.5%), African-American (75.9%), or American Indian or Alaska Native (70.8%) women. During the same period the percentage of expectant mothers that received inadequate prenatal care—care beginning during the third trimester or no prenatal care at all—declined by more than half, from 7.9% to 3.5%. More American Indian or Alaska Natives (7.6%) and African-American women (6%) failed to receive adequate prenatal care than white (3%) or Asian or Pacific Islander (3.1%) women.

Overall, the percentage of women of all races and ethnicity that received early prenatal care increased from the period of 1995–97 to the period of 2001–03. (See Table 1.3.) There was, however, a wide geographic variation in the percentage of women obtaining early prenatal care during the 2001–03 period, from a low of 75.7% of women in the District of Columbia to a high of 89.8% of women in Massachusetts. Within states, the percentage of women that received prenatal care varied widely. For example, in New Jersey less than two-thirds of African-American women (63.5%) received early prenatal care, compared with 89% of white women.

The March of Dimes cited lack of health insurance, transportation, and child care; inconvenient health care provider service hours; unplanned pregnancies; and cultural and personal factors as obstacles preventing expectant mothers from receiving prenatal care.

Early prenatal care can prevent or reduce the risk of low birth weight (LBW). Infants who weigh less than twenty-five hundred grams (five pounds, eight ounces) at birth are considered to be of LBW. Those born weighing less than fifteen hundred grams (three pounds, four ounces) are termed very low birth weight (VLBW). LBW may result from premature birth (infants born before thirty-seven weeks of pregnancy are considered premature), poor maternal nutrition, teen pregnancy, drug and alcohol use, smoking, or sexually transmitted diseases.

Infants who are premature or have LBVs are at greater risk of death and disability than infants of normal weight. About 80% of women at risk for delivering a LBW infant can be identified in the first prenatal visit, and interventions can be made to try to prevent problems. Between 1995 and 2003 the proportion of newborn babies weighing less than twenty-five hundred grams increased from 7.4% to 7.8%. (See Table 1.4.)

As with access to prenatal care, the percent of LBW live births varies by geography, race, and ethnicity. Among non-Hispanic African-Americans, 13.3% of live births weighed less than twenty-five hundred grams, compared with 6.9% of white births, 6.6% of Hispanic or Latino births, 7.3% of American Indian or Alaska native births, and 7.7% of Asian or Pacific Islander births. Nearly 15% of live births to African-American mothers in Colorado were LBW, compared with 5.4% of LBW live births to Hispanic or Latino mothers in Washington. (See Table 1.4.)

The usual length of pregnancy is forty weeks from the first day of the woman's last menstrual period. Infants born prematurely do not have fully formed organ systems. If, however, the premature infant is born with a birth weight comparable to a full-term baby and has organ systems only slightly undeveloped, the chances of survival are great. Premature infants of VLBW are susceptible to numerous risks and are less likely to survive than full-term infants. If they survive, they may suffer from mental retardation, developmental disabilities, and other abnormalities of the nervous system.

A severe medical condition called hyaline membrane disease, or respiratory distress syndrome (RDS), commonly affects premature infants. It is caused by the inability of immature lungs to function properly. Occurring immediately after birth, the disease may cause infant death within hours. Intensive care of affected infants includes the use of a mechanical ventilator to facilitate breathing. Also, premature infants' immature gastrointestinal systems preclude them from taking in nourishment properly. Unable to suck and swallow, they must be fed through a nasogastric feeding tube (nutrient-rich formula enters through a tube inserted into the stomach via the nose).

While ideal birth weight varies based on the expectant mother's ethnicity, the NCHS reports that for women in the United States the average ideal birth weight is approximately 7.5 pounds, which was the average weight of singletons (babies born singly) born in 2002. The percent of babies born with LBW has risen steadily since the mid-1980s, reaching the highest level reported in more than three decades in the 2001–03 period. In Health, United States, 2005 the NCHS also reports that the percent of VLBW infants rose from 1.44% in 2001 to 1.46% in 2002.

LBW and VLBW are major predictors of infant morbidity (illness or disease) and mortality. For LBW infants, the risk of dying during the first year of life is more than five times that of normal-birth-weight infants; the risk for VLBW infants is nearly one hundred times higher. The risk of delivering an LBW infant is greatest among the youngest and oldest mothers; however, many of the LBW births among older mothers are attributable to their higher rates of multiple births. According to the NCHS, in 2002 multiples accounted for nearly two-thirds of all LBW infants delivered to mothers age forty-five and older. Less than 10% of singletons born to mothers age forty-five or older were LBW, compared with 8.7% of births to mothers less than twenty years old. Health, United States, 2005 reports the rate of triplet and higher order multiple births in 2003—187.4 per one hundred thousand live births—has remained relatively stable since 1998, with the greatest increase in multiple births among women age thirty and older.

Birth Weight Influences Risk of Disease

Although the relationship between birth weight and development of disease in adulthood is an emerging field of research, and scientists cannot yet fully explain how and why birth weight is a predictor of health and illness in later life, mounting evidence indicates that both LBW and higher-than-average birth weight are linked to future health problems. Research reveals that LBW infants are more likely than normal-weight infants to develop disease in later life. Male infants with LBW who gain weight rapidly before their first birthdays appear to be at the highest risk. Investigators hypothesize that LBW infants have fewer muscle cells at birth and that rapid weight gain during the first year of life may lead to disproportionate amounts of fat to muscle and above-average body mass. Persons with LBW who later develop aboveaverage body mass are at increased risk for developing diseases such as Type 2 diabetes, hypertension (high blood pressure), cardiovascular disease, and stroke. A 1997 study published in the British journal Lancet examined the medical records of 13,249 men and found the risk of dying from stroke or heart disease was highest for those who weighed 5.5 pounds at birth or less. Those who

weighed more than 8.5 pounds at birth had the lowest rate of mortality from heart attack or stroke.

A study published in the September 2005 issue of the American Heart Association journal Circulation found an inverse relationship between birth weight and cardiovascular disease (heart disease and stroke). In general, rates of both coronary heart disease and stroke decreased with increasing birth weight. The association was strong, did not depend on adjustment for size in later childhood, and was independent of social class and other maternal and pregnancy characteristics (Debbie A. Lawler et al, "Birth Weight Is Inversely Associated with Incident Coronary Heart Disease and Stroke among Individuals Born in the 1950s").

LBW also was linked to childhood asthma in a study published in the March 2001 issue of Archives of Pediatrics and Adolescent Medicine, which found that babies born at 5.5 pounds or less faced the greatest risk of respiratory complications such as asthma. Research also has demonstrated that both LBW and abnormally high birth weight are associated with risk of developing diabetes later in life (Ann-Marie Brooks et al, "Impact of Low Birth Weight on Early Childhood Asthma in the United States").

Evidence also indicates that birth weight is related to risk of developing breast cancer. Valerie A. McCormack and her colleagues at the Department of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, investigated whether size at birth and rate of fetal growth influenced the risk of developing breast cancer in adulthood. The results of the study were published in "Fetal Growth and Subsequent Risk of Breast Cancer: Results from Long Term Follow Up of Swedish Cohort" (British Medical Journal, vol. 326, no. 7,838, February 2003). By examining birth and medical records of 5,358 singleton females born from 1915 to 1929, the investigators determined that size at birth was associated with breast cancer in premenopausal (the stage of reproductive life immediately before the onset of menopause) women age fifty or younger—the larger and longer the baby, the greater the risk. Birth weight or size was not associated with rates of breast cancer in postmenopausal women. Among premenopausal women who weighed four thousand or more grams at birth (eight pounds, fourteen ounces), rates of breast cancer were 3.5 times higher than those women who weighed less than three thousand grams at birth (about six pounds, ten ounces). The investigators concluded that size at birth, including birth weight, length, and head circumference, is associated with risk of breast cancer in women under age fifty.

An analysis performed by Canadian researchers found that infants born either prematurely or with a VLBW were significantly more likely to suffer lower levels of fitness later in life—including less strength, endurance, and flexibility—and a greater risk of health problems as adults. When compared with normal-birth-weight teens, the VLBW teens had lower aerobic capacity, grip strength, leg power, and vertical jump. They were unable to perform as many push-ups, had less abdominal strength as measured by curl-ups, had less lower-back flexibility, and had tighter hamstrings. The VLBW teens reported less previous and current sports participation, lower physical activity levels, and poorer coordination compared with full-term-born control subjects. VLBW teens also had more trouble maintaining rhythm and tempo than their normal-birth-weight peers (Marilyn Rogers et al., "Aerobic Capacity, Strength, Flexibility, and Activity Level in Unimpaired Extremely Low Birth Weight (800 g) Survivors at 17 Years of Age Compared with Term-Born Control Subjects," Pediatrics, vol. 116, no. 1, July 2005, http://pediatrics. aappublications.org/cgi/content/full/116/1/e58).

The only action able to alter the birth weight of an infant is to modify weight gain by the mother during pregnancy. By 2006 health professionals concurred that for normal-weight women the ideal weight gain during pregnancy ranges from twenty-five to thirty-five pounds of fat and lean mass. Further, research published in 2003 revealed that a newborn's birth weight and mother's post-pregnancy weight are influenced not only by how much weight is gained during pregnancy but also by the source of the excess weight. In "Composition of Gestational Weight Gain Impacts Maternal Fat Retention and Infant Birth Weight" (American Journal of Obstetrics and Gynecology, vol. 189, no. 5, November 2003), researcher Nancy F. Butte and her colleagues conducted body scans of sixty-three women before, during, and after their pregnancies and recorded changes in women's weight from water, protein, fat, and potassium—a marker for changes in muscle tissue, one component of lean mass. The researchers found that only increases in lean mass, and not fat mass, appeared to influence infant size. Independent of how much fat was gained by women during pregnancy, only lean body mass increased the birth weight of the infant, with women who gained more lean body mass giving birth to larger infants.

Birth Defects

The March of Dimes Birth Defects Foundation reports that every 3.5 minutes a baby is born with a birth defect, and one in five infant deaths is caused by birth defects. The foundation also notes that an estimated 150,000 babies with birth defects are born each year. A birth defect may be a structural defect, a deficiency of function, or a disease that an infant has at birth (congenital). Some common birth defects are genetic—inherited abnormalities such as Tay-Sachs disease (a fatal disease that generally affects children of eastern European Jewish ancestry) or chromosomal irregularities such as Down syndrome. Other birth defects result from environmental factors—infections during pregnancy, such as rubella (German measles), or drugs used by the pregnant woman. Although the specific causes of some birth defects are unknown, scientists believe that many result from a combination of genetic and environmental factors. The March of Dimes reports that despite research and many medical advances, birth defects have persisted as a leading cause of infant death (after preterm birth and LBW).

NEURAL TUBE DEFECTS

Neural tube defects (NTDs) are abnormalities of the brain and spinal cord resulting from the failure of the neural tube to develop properly during early pregnancy. The neural tube is the embryonic nerve tissue that eventually develops into the brain and the spinal cord. The CDC has reported that about four thousand unborn children are affected with NTDs each year. Of these, approximately twenty-five hundred cases involve infants born with the two most common NTDs—anencephaly and spina bifida (March 3, 1995, http:// www.cdc.gov/mmwr/preview/mmwrhtml/00036442.htm).

ANENCEPHALY

According to the U.S. National Institutes of Health (NIH), anencephaly (absence of a major part of the brain, skull, and scalp) occurs in about four out of ten thousand births (http://www.nlm.nih.gov/ medlineplus/ency/article/001580.htm). The exact number is unknown because many of these pregnancies end in miscarriage. Infants with anencephaly either die before birth (in utero or stillborn) or shortly thereafter.

The incidence of anencephaly decreased significantly from 1991 to 2001, according to the NCHS (http://www.cdc.gov/nchs/data/hestat/spine_anen_tables.pdf). In 1991, 18.4 babies per one hundred thousand live births were reported with the condition; this number dropped to 9.4 in 2001. In 2003, however, the rate had risen to 11.1.

The Birth Defects Monitoring Program (BDMP) of the CDC was discontinued in 1993, making national data on birth defects difficult to come by. Subsequently, twenty states began conducting their own surveillance of NTDs. And in March 1998 the Birth Defects Prevention Act (PL105-168) was passed, "expressing the sense of Congress that birth defects are a major public health problem and need to be addressed."

Some physicians and ethicists feel that even if babies with anencephaly have a brainstem, they should be considered brain dead. Lacking a functioning higher brain, these babies can feel nothing, and they have no consciousness. Others fear, however, that declaring babies with anencephaly dead might be a first step on the "slippery slope" of eventually also declaring dead those with other birth defects, such as spina bifida, another neural tube defect. Spina bifida defects range from mild to severe. Still others are concerned that babies with anencephaly may be kept alive exclusively for the purpose of harvesting their organs for research or transplant at a later date.

SPINA BIFIDA

Spina bifida, which literally means "divided spine," is caused by the failure of the vertebrae (backbone) to completely cover the spinal cord early in fetal development, leaving the spinal cord exposed. Depending on the amount of nerve tissue exposed, spina bifida defects range from minor developmental disabilities to paralysis. The March of Dimes reports that spina bifida affects one in two thousand infants each year (http://www.marchofdimes.com/professionals/681_1224.asp).

Before the advent of antibiotics in the 1950s, most babies with severe spina bifida died soon after birth. With antibiotics and advances in medicine and surgery, some of these newborns now can be saved.

PREVENTION

Scientists now know that daily consumption of 0.4 milligrams (four hundred micrograms) of the B vitamin folic acid by women before and during the first trimester of pregnancy greatly reduces the risk of spina bifida and other birth defects. Because half of all pregnancies in the United States are unplanned or incorrectly timed and because neural tube defects occur during the first month of pregnancy—before most women know they are pregnant—in 1992 the U.S. Public Health Service began recommending that all women of child-bearing age consume 0.4 milligrams of folic acid daily. To comply with a mandate from the U.S. Food and Drug Administration (FDA), as of January 1998 all enriched cereal grain products must be fortified with folic acid. According to the March of Dimes, if all women consumed the recommended amount of folic acid before conception and throughout the first month of pregnancy, as many as 70% of NTDs could be prevented.

The NCHS reports that after a significant increase in the spina bifida rate from 1992 to 1995, there was a significant decline from 1995 to 1999 (http://www.cdc.gov/nchs/data/hestat/spine_anen_tables.pdf). From 1999 to 2002 the rate did not change much, but for the years 1999–2002 the rates were much lower than in 1997. The rate of spina bifida decreased from 20.1 per one hundred thousand live births in 2002 to 18.9 per one hundred thousand live births in 2003. Additionally, a study published in the Journal of the American Medical Association in June 2001 found a 23% decline in the birth prevalence of spina bifida following folic acid fortification of the U.S. food supply (Margaret A. Honein et al, "Impact of Folic Acid Fortification of the US Food Supply on the Occurrence of Neural Tube Defects"). The decline is an indicator of successful efforts to prevent this defect by increasing folic acid consumption among women of childbearing age.

The March of Dimes also found evidence of the effectiveness of education about folic acid consumption to prevent birth defects. A 1995 telephone survey of approximately two thousand English-speaking women ages eighteen to forty-five found that 52% of women surveyed had heard of folic acid, but only 4% knew it helped to prevent birth defects. By 2002, 80% of women surveyed reported hearing of folic acid, and 20% knew it prevented birth defects (http://www.marchofdimes.com/ peristats/ataglance/17.pdf).

BIRTH DEFECTS PREVENTION ACT OF 1998

On April 21, 1998, President Bill Clinton signed into law the Birth Defects Prevention Act (PL105-168) that authorized a nationwide network of birth defects research and prevention programs and called for a nationwide information clearinghouse on birth defects. Dr. Jennifer L. Howse, president of the March of Dimes Birth Defects Foundation, noted: "This legislation will help us find the causes of major birth defects, devise new ways to help prevent them, and better apply what we already know."

On December 3, 2003, the "Birth Defects and Development Disabilities Prevention Act" (H.R. 398 and S. 286) was passed into law. This bill revises and extends the Birth Defects Prevention Act of 1998 to expand and adjust research and reporting requirements. The budget for activities related to the "Birth Defects, Developmental Disabilities, Disability and Health" category for fiscal year 2006 includes $124 million. This funding will be used for a range of disability programs, including those related to fetal alcohol syndrome, autism, attention-deficit/hyperactivity disorder (ADHD), Duchenne type and Becker type muscular dystrophy, developmental disabilities, limb loss, and spina bifida.

INFANT MORTALITY

Since 1940 the infant mortality rate in the United States has declined by approximately 85%—from about forty-seven deaths per one thousand live births in 1940 to less than seven deaths per one thousand live births in 2003. (See Figure 1.1.) The NCHS reports that in 2002 the infant mortality rate rose for the first year since 1958, from 6.8% in 2001 to 7%. An analysis of this slight increase revealed that it was attributable to deaths that occurred during the first week of life, which were probably related to an increase in the number of VLBW infants. In 2003 there was a small but not statistically significant decline in the infant mortality rate. (See Table 1.5.)

Advances in neonatology (the medical subspecialty concerned with the care of newborns, especially those at risk) have contributed to the huge decline in infant death rates. Infants born prematurely or with LBWs, who were once likely to die, can survive life-threatening conditions because of the development of neonatal intensive care units (NICUs). Improved access to health care also has contributed to the decline, as well as public health initiatives that have educated Americans about how to prevent sudden infant death syndrome (SIDS)—specifically the "Back to Sleep" campaign teaching caregivers to place sleeping infants on their backs. Nonetheless, despite the tremendous improvements in neonatal treatment, increased access to care, and more widespread education, during the years 2000–02 African-American infants were more than twice as likely as white and Hispanic infants to die before their first birthdays. (See Figure 1.2.) In 2002 the national death rate for African-American infants was 13.8 per one thousand live births, compared with 5.8 per one thousand live births for white infants and 5.6 per one thousand live births for Hispanic infants. (See Table 1.6.)

Table 1.7 shows the U.S. infant mortality rate compared with those of other industrialized nations. The United States had higher infant mortality rates than twenty-seven other countries in 2002 and at least twice the rate of infant deaths as Sweden, Spain, Singapore, Norway, Japan, Hong Kong, and Finland.

LIFE EXPECTANCY

During the twentieth century, advances in public health and medical care helped Americans to lead longer, healthier lives. Along with infant mortality, life expectancy rates are an important measure of the health of the population. Life expectancy at birth is strongly influenced by infant and child mortality. Life expectancy in adulthood reflects death rates at or beyond specified ages and is independent of the effect of mortality at younger ages.

Figure 1.3 shows the upward trend from 1970 to 2003 in U.S. life expectancy for males and females at birth. The numbers in Table 1.8 reveal that throughout the twentieth century, life expectancy increased dramatically, from 46.3 years in 1900 to 74.3 years in 2000 for males and from 48.3 years in 1900 to 79.7 in 2000 for females. In Health, United States, 2005, the NCHS additionally reports that life expectancy at age sixty-five also increased over the twentieth century. Unlike life expectancy at birth, which rose early in the twentieth century, much of the rise in life expectancy at age sixty-five occurred after 1950 in response to improved access to health care, advances in medicine, healthier current lifestyles, and better health throughout the lifespan.

In 2002 life expectancy at birth for the total population reached a then-record high of 77.3 years, up from 75.4 years in 1990. The CDC estimated that in 2005 life expectancy at birth had increased to 77.6 years. Life expectancy at birth for females in 2002 (79.9 years) outstripped that of males (74.5 years) by 5.4 years. White females in 2002 had the longest life expectancy, 80.3 years, compared with 75.6 years for African-American females, 75.1 years for white males, and 68.8 years for African-American males. (See Table 1.8.)

Many factors contribute to the significantly lower life expectancy for African-American men. In addition to issues of access to health care, some observers suggest that African-American males must deal with greater social, economic, and psychological stress than other men, leaving African-American men more susceptible to various diseases. Among African-American males in 2000–02, the observed number of deaths resulting from homicides, human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS), and cardiovascular disease was much higher than would be expected based on their proportion in the overall population. (See Table 1.9 for causes of death of African-American males compared with other populations.)

As deaths from infectious diseases declined, mortality from chronic diseases, such as heart disease, cancer, and diabetes, increased. Table 1.9 displays the ten leading causes of death in the United States in 1980 and 2002, and Figure 1.4 shows the rate of overweight and obesity between 1960 and 2002, with a sharp increase beginning in 1976–80. Overweight and obesity are considered contributing factors to at least four of the ten leading causes of death in 2002—diseases of the heart, malignant neoplasms (tumors), cerebrovascular diseases (diseases affecting the supply of blood to the brain), and diabetes mellitus. (Obesity also may be implicated in another leading cause of death—kidney disease or chronic renal failure, which are called nephritis, nephrotic syndrome, and nephrosis in Table 1.9.) Table 1.9 also reveals the rise of diabetes as a cause of death. In 1980 it was the seventh-leading cause of death, claiming nearly thirty-five thousand lives. By 2002 it rose to the sixth-leading cause of death overall, claiming more than seventy-three thousand lives and being mentioned on the death certificates of more than twice as many additional deaths. Epidemiologists and medical researchers believe that the increasing prevalence of diabetes in the U.S. population and the resultant rise in deaths attributable to diabetes are direct consequences of the obesity epidemic in America.

In 2005 S. Jay Olshansky and his colleagues at the University of Illinois suggested that the steady rise in life expectancy the U.S. enjoyed during the past two centuries may soon come to an end. The investigators used obesity prevalence data and previously published estimates of years of life lost from obesity to project life expectancy. Instead of using historical trends to forecast life expectancy, they calculated in reverse, assessing the fall in death rates that would occur if all obese Americans had a normal weight. Their projections revealed that within fifty years obesity is likely to reduce the average life expectancy in the United States by at least two to five years from its 2005 level of 77.6 years. The impact of obesity and its health consequences on life expectancy was considered larger than cancer or heart disease (S. Jay Olshansky et al., "A Potential Decline in Life Expectancy in the United States in the 21st Century," New England Journal of Medicine, vol. 352, no. 11, March 17, 2005).

MORTALITY

Years of Potential Life Lost

"Years of potential life lost" (YPLL) is a term used by medical and public health professionals to describe the number of years deceased persons might have lived if they had not died prematurely (before their life expectancy). In 2002 most YPLL resulted from malignant neoplasms (cancer), heart disease, and unintentional injuries (accidents). (See Table 1.10.)

The increase in life expectancy in the twentieth century has meant a decrease in the YPLL rate. In 1980 a total of 10,448.4 years per one hundred thousand population were lost to people younger than age seventy-five; by 2002 that number had declined to 7,499.6 total years lost. (See Table 1.10.) Although heart disease remains the number-one killer in the United States, it has been responsible for a smaller proportion of YPLL since 1980 (2,238.7 in 1980 and 1,212.7 in 2002). Similarly, years lost to cerebrovascular diseases (e.g., strokes), liver diseases, pneumonia, and motor vehicle accidents also have declined since 1980. And after increasing dramatically between 1980 and the mid-1990s, years lost to HIV infection decreased almost fourfold between 1995 and 2002. However, YPLL rates for diabetes increased over this same period and chronic lower respiratory diseases remained roughly the same.

With the exception of suicide, the YPLL due to all causes for African-Americans was significantly higher than for white males and females. In 2002, for all causes, African-Americans lost 12,401 years of potential life per one hundred thousand population, compared with 6,936.6 years for white Americans. African-Americans lost considerably more years of life to heart disease, cerebrovascular diseases, cancers, HIV, and homicide than did whites. (See Table 1.10.)

RACIAL AND GENDER DIFFERENCES

Significant racial and ethnic variations exist in the ten leading causes of death. (See Table 1.9.) In 2002 chronic liver disease and cirrhosis were not listed as leading causes of death for all Americans; they were, however, listed as leading causes of death among all men, American Indian or Alaskan Natives, and Hispanics. In contrast, homicide was a leading cause of death for African-American and Hispanic men; it ranked ninth for American Indian or Alaska Native men and was the tenth-leading cause of death of Asian or Pacific Islander men. In 2002 homicide did not rank as a leading cause of death for women of any race/ethnicity.

AGE DIFFERENCES

In 2002, as would be expected, death rates were highest for people age eighty-five and older (14,828.3 per one hundred thousand population). From age twenty-five on, death rates doubled with each additional decade. (See Table 1.11.)

The ten leading causes and numbers of deaths vary by age. In 2002 accidents (unintentional injuries) were the leading cause of death for children one to four years of age, followed by congenital malformations and homicide. Although children five to fourteen years old were also most likely to die from accidents, cancer was the second most prevalent cause of death, followed by congenital malformations, homicide, and suicide. (See Table 1.12.)

Accidents (unintentional injuries) were the leading cause of death in 2002 for young people ages fifteen to twenty-four. Homicide was the second-leading cause of death, followed by suicide. Cancer was the fourth-leading cause of death among this age group. (See Table 1.12.)

Among adults ages twenty-five through forty-four in 2002, accidents were the most frequent cause of death, and cancer was second. Heart disease and suicide were the third- and fourth-leading causes, respectively, followed by homicide and HIV disease. (See Table 1.12.)

Among adults forty-five through sixty-four years old, cancer and heart disease were ranked the first- and second-leading causes of death, respectively. Among those age sixty-five and older, these two categories were reversed. (See Table 1.12.)

"Actual" Cause of Death

Actual causes of death are defined by the CDC as lifestyle and behavioral factors such as smoking and physical inactivity that lead to leading killers, including heart disease, cancer, and stroke. According to a CDC fact sheet released in March 2004 (http://www.cdc.gov/od/oc/media/pressrel/fs040309.htm), in 2000 the most common actual causes of death in the United States were tobacco (responsible for four hundred and thirty-five thousand deaths), poor diet and physical inactivity (four hundred thousand deaths), alcohol consumption (eighty-five thousand deaths), microbial agents (for example, influenza and pneumonia; seventy-five thousand deaths), toxic agents (for example, pollutants and asbestos; fifty-five thousand deaths), motor vehicle accidents (forty-three thousand deaths), firearms (twenty-nine thousand deaths), sexual behavior (twenty thousand deaths), and illicit use of drugs (seventeen thousand deaths). Taken together, these accounted for about half of all 2.4 million U.S. deaths in 2000.

Many epidemiologists and other public health researchers contend that sedentary Americans are eating themselves to death, and they fear that the adverse health outcomes, in terms of morbidity and mortality, resulting from unhealthy eating and inactivity will soon outpace tobacco as the top actual and preventable cause of death. The CDC reports the gap between the two in 2000 was substantially narrower than in 1990, when poor diet and inactivity caused three hundred thousand deaths (14%), compared with four hundred thousand for tobacco (19%).

SELF-ASSESSED HEALTH STATUS

The NCHS regularly asks respondents to the National Health Interview Survey (NHIS) to evaluate their health status. Figure 1.5 shows that from 1997 through 2005 the percentage of people who considered their health to be excellent or very good was relatively unchanged, ranging from a high of close to 70% in 1998 but hovering around two thirds for most years. From January-June 2005, 66.4% of respondents assessed their health as excellent or very good.

Overall, men were slightly more likely to rate their health as excellent. (See Figure 1.6.) However, for both men and women, the percentage who considered their health as excellent or very good decreased with advancing age—81.5% for those younger than age eighteen; 65.6% for those age eighteen to sixty-four; and 38.5% for those age sixty-five and older. (See Figure 1.7.) Compared with the 70.1% of white survey respondents who assessed their health as excellent or very good, fewer African-American (57.7%) and Hispanic (56.8%) survey respondents rated their health status as excellent or very good. (See Figure 1.8.)

The Gallup Organization also queries Americans about their own physical and mental health in an annual health and health care poll. A November 2005 Gallup Poll found that more than one-quarter (28%) of Americans said their health was excellent, and an additional 50% said their health was good. (See Table 1.13.) Similarly, most Americans describe their mental health or emotional well-being optimistically. More than three-quarters of Americans characterized their mental health as excellent or good (85%), while less than one-fifth described it as fair or poor (15%). (See Figure 1.9.)

The Gallup Organization also found evidence of the "mind-body connection." Ninety-two percent of survey respondents who described their physical health as excellent or good also viewed their mental health as excellent or good. In contrast, just 64% of those who rated their physical health as fair or poor said their mental health was excellent or good. Almost one-third (31%) of the respondents who described their physical health as excellent or good said that their emotional well-being was not good for one or more days in the past month, while nearly twice as many (60%) who rated their physical health as fair or poor were similarly distressed. (See Figure 1.10.)