Infant Mortality -- United States, 1990
The infant mortality rate for the United States for 1990 -- 9.2 infant deaths per 1000 live births -- was the lowest rate ever recorded and represented a decrease of 6% from the rate of 9.8 for 1989. This report summarizes 1990 infant mortality data based on information from birth and death certificates compiled by CDC's National Center for Health Statistics' (NCHS) Vital Statistics System (1) and compares findings with those for 1989.
In this report, cause-of-death statistics are based on the underlying cause of death * reported on the death certificate by the attending physician, medical examiner, or coroner in a manner specified by the World Health Organization. Race for infant deaths is tabulated by race of decedent; race for live births (which comprise the denominator of infant mortality rates) is by race of mother. Race differences are given only for black and white infants because the Linked Birth/Infant Death Data Set -- used to more accurately estimate infant mortality rates for other racial groups -- was not yet available for 1989 and 1990.
A total of 38,351 infants died during 1990, compared with 39,655 during 1989. The mortality rate for black** infants in 1990 (18.0 per 1000) decreased 3% from the rate in 1989 (18.6 per 1000); for white** infants, the rate decreased 6% (from 8.1 in 1989 to 7.6 in 1990). From 1989 through 1990, the neonatal (infants aged less than 28 days) mortality rate decreased 6% (6.2 and 5.8 per 1000, respectively). For black infants, the rate decreased 3% (11.9 to 11.6); for white infants, the rate decreased 6% (5.1 to 4.8). The postneonatal (infants aged 28 days-11 months) mortality rate decreased 6%, from 3.6 in 1989 to 3.4 in 1990. For black infants, the postneonatal mortality rate decreased 4% (from 6.7 to 6.4), and for white infants, 3% (from 2.9 to 2.8).
From 1989 through 1990, the infant mortality rate decreased for eight of the 10 leading causes of infant death. The largest decreases were for respiratory distress syndrome (24%), accidents *** and adverse effects (9%), and sudden infant death syndrome (SIDS) (7%). The two increases were for the categories of newborn affected by maternal complications of pregnancy (5%) and intrauterine hypoxia and birth asphyxia (2%).
The rank order of the 10 leading causes of infant death differed by race (Table 1). The first four leading causes of death were the same for black and white infants, although their rank order differed. These same four causes accounted for 49% of all deaths among black infants and for 56% of all deaths among white infants; the remaining six of the 10 leading causes accounted for 16% and 15% of the total deaths for black and white infants, respectively. For black infants, the leading cause of death was disorders relating to short gestation and unspecified low birthweight (LBW) (less than 2500 g at birth) (279.4 deaths per 100,000 live births), accounting for 16% of all deaths among black infants. For white infants, the leading cause of death was congenital anomalies (195.1 deaths per 100,000 live births), accounting for 26% of all deaths among white infants.
In 1990, the risk of dying within the first year of life was 2.4 times greater for black than for white infants. For each of the leading causes of death, the risk of death was higher for black than for white infants, although there were large variations in the magnitude of the excess by cause. The highest black-to-white rate ratios were associated with disorders relating to short gestation and unspecified LBW (4.6:1), pneumonia and influenza (3.0:1), respiratory distress syndrome and newborn affected by maternal complications of pregnancy (2.6:1 each), and infections specific to the perinatal period (2.5:1). The lowest ratios were associated with congenital anomalies (1.1:1) and SIDS and newborn affected by complications of placenta, cord, and membranes (2.1:1 each).
Three of the 10 leading causes of infant death accounted for 41% of the difference in infant mortality between black and white infants: disorders relating to short gestation and unspecified LBW (21%), SIDS (12%), and respiratory distress syndrome (8%).
Reported by: Div of Reproductive Health, National Center for Chronic Disease Prevention and Health Promotion; Div of Vital Statistics, National Center for Health Statistics, CDC.
Editorial Note: Infant mortality is one of the most widely used general indices of health in the United States and other countries. The infant mortality rate in the United States remains higher than that in many other developed countries. In 1988 (the most recent year for which these data are available), the infant mortality rate in the United States ranked 23rd (2), a decline in rank from 1980 (20th) (3).
During the 1970s, the U.S. infant mortality rate decreased by 5% per year. However, the rate of decrease slowed to an annual average of 3% during 1980-1989. The decrease of 6% for 1989-1990 predominantly reflects the rapid decrease in mortality from respiratory distress syndrome (accounting for 36% of the decrease from 1989 to 1990) -- possibly because of improvements in medical management of this condition (4).
Differences in infant mortality rates by race may reflect differences in factors such as socioeconomic status, access to medical care, and the prevalence of specific risks. For example, infants of mothers of low socioeconomic status are at increased risk of death (5). In 1990, nearly three times as many black as white infants (56% versus 20%) were members of families with incomes below the poverty level (Bureau of the Census, unpublished data, 1992). In addition, because of income differentials, black women may be less likely to have health insurance that covers the costs of care for pregnancy and childbirth (6) and therefore unable to obtain adequate care (7).
LBW is an important intermediate variable between some risk factors and infant mortality. In 1987 (the latest year for which data are available), 6.9% of infants were born with LBW; however, 61% of all infant deaths occurred among these infants. In 1990, 13.3% of black infants were born with LBW, in comparison with 5.7% of white infants (7 ). Although race differentials in mortality from predominantly postneonatal causes of infant death (e.g., SIDS, accidents and adverse effects, and pneumonia and influenza) are important (8), most of the causes of death for which black infants are at substantially elevated risk of death are closely associated with LBW. For three of the four causes of infant death with the highest mortality rate ratios (i.e., disorders relating to short gestation and unspecified LBW, respiratory distress syndrome, and newborn affected by maternal complications of pregnancy), more than 95% of the 1987 deaths occurred among LBW infants (CDC, unpublished data, 1992).
One of the 1990 national health objectives was to reduce the overall infant mortality rate to 9.0 deaths per 1000 live births (9); the recorded rate of 9.2 for 1990 nearly reached that goal. A year 2000 national health objective is to reduce the overall infant mortality rate to no more than 7 per 1000 live births (objective 14.1) (10). If the average annual decrease of 3% for the total population during the 1980s continues, the overall infant mortality objective for the year 2000 will be achieved.
Strategies to achieve the national health objective for reducing infant mortality should consider the heterogeneity of factors accounting for infant mortality in the United States. For example, reducing mortality from disorders related to short gestation and unspecified LBW will require improved understanding of etiologic risk factors for preterm delivery. Reduction of deaths related to maternal complications of pregnancy and intrauterine hypoxia and asphyxia will require both expansion of access to prenatal care and assessment of the adequacy of the content of care (11). Continued high mortality rates from pneumonia and influenza and injury suggest that prevention programs should be universally available to assure vaccinations and to encourage the use of car seats and home-based prevention measures (12).
While total infant mortality declined in 1990, the gap in infant mortality between black and white infants increased -- this pattern underscores the need to distinguish those factors associated with the decline from those factors that account for the disparity (13). Differences in socioeconomic status and access to care do not entirely explain the disparity (14), and suggest that other factors, which may not be available in routinely collected data, need to be examined.
Hyattsville, Maryland: US Department of Health and Human Services, Public Health Service, CDC, 1993. (Monthly vital statistics report; vol 41, no. 7, suppl).
2. NCHS. Health, United States, 1991. Hyattsville, Maryland: US Department of Health and Human Services, Public Health Service, CDC, 1992; DHHS publication no. (PHS)92-1232.
3. NCHS. Health, United States, 1988. Hyattsville, Maryland: US Department of Health and Human Services, Public Health Service, CDC, 1989; DHHS publication no. (PHS)89-1232.
4. Long W, Corbet A, Cotton R, et al. A controlled trial of synthetic surfactant in infants weighing 1250 g or more with respiratory distress syndrome. N Engl J Med 1991;325:1696-1703.
5. Gould JB, Davey B, LeRoy S. Socioeconomic differentials and neonatal mortality: racial comparison of California singletons. Pediatrics 1989;83:181-6.
6. Alan Guttmacher Institute. Blessed events and the bottom line: financing maternity care in the United States. New York: Alan Guttmacher Institute, 1987.
7. NCHS. Advance report of final natality statistics, 1990. Hyattsville, Maryland: US Department of Health and Human Services, Public Health Service, CDC, 1993. (Monthly vital statistics report; vol 41, no. 9, suppl).
8. MacDorman MF, Rosenberg HM. Trends in infant mortality by cause of death and other characteristics, 1960-88. Hyattsville, Maryland: US Department of Health and Human Services, Public Health Service, CDC, 1993. (Vital and health statistics; series 20, no. 20).
9. Public Health Service. The 1990 health objectives for the nation: a midcourse review. Washington, DC: US Department of Health and Human Services, Public Health Service, 1986. 10. Public Health Service. Healthy people 2000: national health promotion and disease prevention objectives -- full report, with commentary. Washington, DC: US Department of Health and Human Services, Public Health Service, 1991; DHHS publication no. (PHS)91-50212. 11. Public Health Service. Caring for our future: the content of prenatal care -- a report of the Public Health Service Expert Panel on the Content of Prenatal Care. Washington, DC: US Department of Health and Human Services, Public Health Service, 1989. 12. Hinman AR. Immunizations in the United States. Pediatrics 1990;86:1064-6(suppl). 13. Wise P. The social context of race and infant mortality: history and public policy. Am J Prev Med (in press). 14. Schoendorf KC, Hogue CJR, Kleinman JC, Rowley D. Mortality among infants of black as compared with white college-educated parents. N Engl J Med 1992;326:1522-6.
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