Asphyxia neonatorum

Infant mortality is the incidence of death that occurs in the first year after birth, expressed in relation to every 1,000 live births. Infant mortality is commonly divided into two categories: neonatal deaths (occurring during the first 27 days after birth) and postneonatal deaths (occurring from the age of 28 days to one year). Infant mortality is considered an important indicator of the general level of health for a given population.

Toward the end of the 19th century, before the widespread recognition that bacteria was a major cause of illness, rates of infant mortality throughout the world were much higher than they are today. It was common for 20% or more of all infants in many populations to die before they reached their first birthday, and often mortality rates were even higher for children between the ages of one and five. In the last years of the 19th century, large areas of Russia had an infant mortality rate of nearly 28%. In 1901, the infant mortality rate in England, birthplace of the industrial revolution and capital of a global empire, was 16%. By 1930 the number of infant deaths had declined dramatically in many countries as the causes of infection came to be understood. Most progress up to this point was due to precautions such as hand washing and sterilization of milk rather than to actual medical advances, since antibiotics and sulfa drugs--the first medications that were really effective in fighting infection--were not developed until the late 1930s and 1940s. Although data on infant mortality in the developing nations is much less complete than the figures for the developed world, it is clear that the world's poorer countries have made dramatic progress in lowering infant mortality in the 20th century, due in large part to public health programs, especially those that have combated malaria through mosquito control. Availability of medication and immunization have also played a major role in improving infant health in developing nations.

In 1993 the infant mortality rate worldwide was 69 deaths per 1,000 live births, according to figures released by the United Nations Population Fund (the U.S. Census Bureau figures are slightly lower). The U.N. also reported an average infant mortality rate for the world's industrialized nations of 12 deaths per 1,000 live births. According to the U.S. Census Bureau's World Population Profile, the highest ratio of infant deaths (177 per 1,000 live births) was found in the Western Sahara and the lowest (four per 1,000) in Japan. The 1993 infant mortality rate in the United States was 8.4 per 1,000, ranking it twenty-second among the world's developed nations (a rank it maintained over the following two years, according to preliminary data for 1994 and 1995). The relatively high rate of infant deaths in the U.S. compared to Japan and Western Europe is largely accounted for by high infant mortality rates among low-income minority populations. Overall, the rate of infant mortality for blacks is more than twice that for whites (16.5 per 1,000 as opposed to 6.8 in 1993). In addition to the difference in the mortality figures themselves, the figures for blacks have declined at a disproportionately slower rate than those for whites. In 1950 the infant mortality rate for blacks was 1.6 times as high as that for whites; in 1991 it was 2.2 times as high. The 1993 statistics for infant mortality in the U.S. list the following as the 10 leading causes of death: 1) birth defects; 2) sudden infant death syndrome (SIDS); 3) respiratory distress syndrome; 4) disorders associated with prematurity and low birth weight; 5) pregnancy complications that affect newborns; 6) oxygen deprivation, either before or during birth (hypoxia and asphyxia neonatorum, respectively); 7) infections present during the period of birth; 8) accidents; 9) complications during birth; and 10) pneumonia or influenza. The first four causes collectively accounted for 54% of all infant deaths.

A cluster of interrelated environmental factors is associated with infant mortality in the United States. These include poverty, inadequate prenatal care, cutbacks in federal programs, a high rate of teenage pregnancies, and use of drugs, alcohol, and tobacco during pregnancy. The factor most often cited as responsible for the lower rates of infant mortality in other developed nations is the universal availability of free prenatal and maternal health care. According to the U.S. Department of Health and Human Services, in 1990 only 61% of African American women received prenatal care in the first trimester of pregnancy. Even when free care is available, low-income women often face significant barriers in obtaining it. They may be unable to take time off work for the lengthy waits that clinic visits often require.

The principal way environmental factors such as poor prenatal care affect infant health is through birth weight. Low birth weight--defined as weight under 5.5 pounds--is responsible for 75% of neonatal deaths and 60% of postneonatal deaths. (Advanced medical technology makes it possible to save many more low-birth-weight babies than could have been saved in the past.) In addition to being considered a leading cause of infant mortality in its own right, low birth weight is also associated with the top three other causes--congenital anomalies (birth defects), sudden infant death syndrome, and respiratory distress syndrome. Thirty-one other countries have a lower incidence of low-birth-weight deliveries than that of the United States. Known risk factors for low birth weight are smoking, drug and alcohol consumption during pregnancy, and teen pregnancy. (In Japan, which has the world's lowest rate of infant mortality, under 1% of mothers are teenagers, compared with 13% in the United States.) Other factors thought to be associated with the relatively high levels of low birth weight among infants born in the U.S. include lower levels of social support, including marital support.

Further Reading

For Your Information

Books

• Boone, Margaret S. Capital Crime: Black Infant Mortality in America. Newbury Park: Sage, 1989.
• Institute of Medicine. Preventing Low Birthweight. Washington, DC: National Academy of Sciences Press, 1985.
• Sears, William. SIDS: A Parent's Guide to Understanding and Preventing Sudden Infant Death Syndrome. Boston: Little, Brown, 1995.
• Tinker, Anne. G., and Marjorie A. Koblinsky. Making Motherhood Safe. Washington, DC: World Bank, 1993.
• U.S. Congress, House Select Committee on Hunger. An Examination of Barriers to Pre- and Postnatal Care for High-Risk Women and Infants. Washington, DC: Government Printing Office, 1992.

Gale Encyclopedia of Childhood & Adolescence. Gale Research, 1998.