Infant mortality - United States, 1993

Morbidity and Mortality Weekly Report, March 15, 1996

The 1993 final infant mortality (death before age 1 year) rate for the United States--infant 8.4 deaths per 1000 live-born infants-was the lowest rate ever recorded and represented a decrease of 1.8% from the rate of 8.5 for 1992. Based on provisional data for 1994, the declining trend in infant mortality continued through 1994 (rate: 7.9) (1). This report uses data from birth and death certificates compiled by CDC (2) to characterize infant mortality in 1993 and compares the findings with those for 1992.

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. Because race reflects differing distributions of several risk factors for infant death (e.g., low birthweight [LBW] [<2500 g (<5 lbs 9 oz) at birth]) and is useful for identifying groups at greatest risk for infant death, this analysis examines race-specific mortality rates. Numerators for infant mortality rates (infant deaths) were tabulated by race of infant; denominators for rates (live-born infants) were tabulated by race of mother. Rates are presented only for white and black infants because the Linked Birth/Infant Death Data Set (used to more accurately estimate infant mortality rates for other racial groups) was not available for 1992 and 1993. Numbers for white and black infants include both Hispanic and non- Hispanic infants.

In 1993, a total of 34,466 infants died in the United States, compared with 38,910 in 1992. The mortality rate for white infants in 1993 (6.8 per 1000) decreased 1.4% from the rate in 1992 (6.9), and the rate for black infants in 1993 (16.5) decreased 1.9% from the rate in 1992 (16.8).

Declines in race-specific rates also varied by age at death. From 1992 through 1993, the overall neonatal mortality (death before age 28 days) rate decreased 1.9% (5.4 to 5.3); for white infants, the rate remained constant (4.3), and for black infants, the rate decreased 1.0% (10.8 to 10.7). The overall postneonatal mortality (death at age 28 days-11 months) rate decreased 2.2% (3.1 to 3.0 per 1000); for white infants, the rate decreased 4% (2.6 to 2.5), and for black infants, 3.5% (6.0 to 5.8). in 1993, the risk for death during the first year of life for black infants remained 2.4 times greater than for white infants.

Among the 10 leading causes of infant death, the first four (congenital anomalies, sudden infant death syndrome, disorders relating to short gestation and unspecified LBW, and respiratory distress syndrome [RDSI) accounted for 54% of all infant deaths in 1993 (Table 1). For white infants, these causes also accounted for 54% of deaths, and for black infants, 51% of deaths.

[TABULAR DATA 1 OMITTED]

From 1992 to 1993, the infant mortality rate decreased for seven of the 10 leading causes of infant death and increased for three causes (Table 1). For white infants, the rate also decreased for seven of the 10 causes; however, for blacks, the rate decreased for six of the 10 causes. Race-specific differences in infant mortality also were reflected in the rank order of the leading causes of infant death and in the rate of change of specific causes (Table 1). For white infants, the largest decrease in rates was for RDS (International Classification of Diseases, Ninth Revision [ICD-9], code 769) (15.5%), and the largest increase, disorders relating to short gestation and LBW (ICD-9 code 765) (16.1%). For black infants, the largest decrease was for pneumonia and influenza (ICD-9 codes 480-487) (16.8%), and the largest increase, infections specific to the perinatal period (ICD-9 code 771) (9.3%). The decrease in RDS for black infants was <1%.

Reported by: Div of Reproductive Health, National Center for Chronic Disease Prevention and Health Promotion, Mortality Statistics Br, Div of Vital Statistics, National Center for Health Statistics, CDC.

Editorial Note: The infant mortality rate is a standard index of health. In 1991 (the most recent year for which comparative data are available), the U.S. infant mortality rate ranked 24th among countries or geographic areas with a population of >1 million (3). Two national health objectives for the year 2000 are 1) to reduce the overall infant mortality rate to no more than 7 per 1000 (objective 14.1) and 2) to reduce the rate among black infants to no more than 11 per 1000 (objective 14.1a) (4). Based on the findings for 1993, attaining these goals will require an average annual decrease of 2.6% in the overall infant mortality rate and a 3.6% annual decrease in the rate for black infants.

In 1993, disorders relating to short gestation and unspecified LBW was the third leading cause of infant death overall, and the leading cause for black infants. During 1992-1993, mortality rates for this cause increased 8.4%, and during 1985-1993 increased 24%. However, based on data about infant birthweight or gestational age available in linked birth and infant death files, recent reductions in the misclassification of infant deaths to this cause may have obfuscated the true increase. If the number of deaths from disorders relating to short gestation and unspecified LBW continue to increase, the year 2000 objectives may not be attained.