Differences in neonatal mortality by race, income, and prenatal care.

To determine the extent to which the social and physical environment affects the association between prenatal care and black pregnancy outcome in Chicago, we performed a stratified analysis of 1982-1983 Illinois vital records and 1980 United States census income data. Median family income of the mother's census tract was used as the ecologic variable. In very-low-income census tracts (less than $10,000 per year), 40% of blacks and 47% of whites received adequate prenatal care. There was no racial disparity in the percentage of low-birth-weight infants attributed to inadequate prenatal care among poor mothers. For mothers who resided in moderate-income areas ($20,001 to $30,000 per year), 50% of blacks and 67% of whites received adequate prenatal care. Although adequate (compared to inadequate) prenatal care was associated with improved birthweight distribution independent of community income, only in moderate-income areas was it related to black neonatal survival. For term black infants who received adequate prenatal care, residence in impoverished areas was associated with a nearly fourfold greater neonatal mortality rate (deaths per 1000 live births): 5/1000 vs 1/1000; RR = 3.8 (1.3-11.0). We conclude that place of residence is an important risk factor for black neonatal mortality.