Racial differences in gestational age-specific neonatal morbidity: further evidence for different gestational lengths

We sought to quantify the gestational age-specific morbidity of black vs white neonates.

This was a population-based retrospective cohort study of singleton live births in Ohio from 2006 through 2007. The primary outcome was a composite of adverse neonatal outcomes of ≥ 1 morbidity: Apgar score < 7 at 5 minutes, assisted ventilation > 6 hours, seizures, or neonatal transport to a tertiary care facility. Generalized linear regression estimated the relative risk of adverse neonatal outcome by week of gestation after adjustment for influential coexistent risk factors.

The frequency distribution curve of composite morbidity by gestational age were similar, but shifted to left (earlier gestational age) for black compared with white neonates. Adverse outcome was lower for black compared with white births at each preterm week of gestational age. The lowest adverse outcome rate for black neonates was at 38 weeks and 39 weeks for white neonates, each increasing by week of gestation thereafter.

These data suggest that pregnancies in black women perhaps have a shorter physiologic gestational length.