A hypothesis to explain paradoxical racial differences in neonatal mortality.

We suggest an explanation for a pediatric paradox: the low-birthweight-specific (LBW) neonatal mortality rate (NMR) for black infants is less than the NMR for white infants, even though the overall NMR for black infants is about twice the overall NMR for white infants. Analyzing the Delivery Interview Program data set--a large matrix of information collected at the Boston Hospital for Women (now the Brigham and Women's Hospital)--we found that, overall, black infants' gestations are about four days shorter than white infants'. However, after stratifying by birthweight, we found a reversal in our data, namely, LBW (< 2,500 g) black infants' gestations are seven days longer than the gestations of LBW white infants. We believe that this increased chronological maturity may account for some of the survival advantage of the LBW black infant compared with the LBW white infant of the same weight.