Racial differences in temporal changes in newborn viability and survival by gestational age

This study examines trends in the rates of very preterm, moderately preterm and gestational age-specific neonatal mortality, and in the gestational age limit of viability in South Carolina (SC) from 1975 to 1994. We also investigate whether trends were similar between African-Americans and Whites. We hypothesised that disproportionate reductions in gestational age-specific mortality, rather than any major changes in the gestational age distributions of either race group, underlie any increasing racial disparity in overall mortality rates. During 1975-94, single livebirths, who were born to mothers resident in SC and were either White or African-American based on recorded maternal race, were selected for the investigation. We define the gestational age limit of viability as the gestational age at which greater than or equal to 50% of infants in the population died within 28 days of life. Although preterm percentages have not improved, there was a marked decline in neonatal mortality. Gestational age-specific neonatal mortality decreased for both race groups, although there were greater reductions for White preterm infants. By the end of the study period, the African-American neonatal mortality rate was 2.3 times that of Whites and the gestational age at which 50% of newborns died within 28 days of life was 24.5 weeks for Whites and 23.9 weeks for African-Americans. The ongoing decline in neonatal mortality continues to be mainly due to reductions in gestational age-specific neonatal mortality, probably related to high-risk obstetric and neonatal care. Technological developments in these areas may have differentially benefited Whites, resulting in an increasing racial disparity in neonatal mortality rates. Preterm African-American infants no longer have a marked survival advantage over White infants, even at the gestational age limit of viability.