Disparate black and white neonatal mortality rates among infants of normal birth weight in Chicago: a population study

Abstract

To determine the extent to which disparities in risk status and access to tertiary care affect racial differences in neonatal mortality rates among normal birth weight infants, we conducted a vital records study concerning normal weight black (N = 44,399) and white (N = 48,146) singleton births in Chicago. Neonatal mortality rate among black infants was twice that among white infants (3.3 deaths per 1000 births vs 1.5 deaths per 1000 births); the unadjusted black relative risk equaled 2.2 (95% confidence interval, 1.7 to 2.9). Because prematurity, growth retardation, congenital anomalies, low Apgar scores at 5 minutes, teenage mothers, and poverty were more common among black infants, multivariate analyses were performed. The disparity in mortality rate was greatest between black and white infants with none of these risk factors; relative risk for black infants equaled 3.6 (95% confidence interval, 2.0 to 6.7). Approximately 30% of all deaths of black infants were attributable to birth in nontertiary hospitals. When the confounding variables, including hospital of birth, were put into a multivariate logistic-regression model, the adjusted relative risk estimate (odds ratio) for black infants equaled 1.5 (95% confidence interval, 1.1 to 2.0). Traditional risk factors fail to explain the racial disparity in neonatal mortality rate among normal birth weight infants. Level of perinatal care available, or some factor closely related to this level, is an important determinant of neonatal chance of survival for normal birth weight urban black infants.