Wisconsin neonatal mortality by race/ethnicity, birthweight, and prematurity: 1991-2005

The proportion of the neonatal deaths to the infant deaths has gradually increased over time, and accounted for more than two-thirds of Wisconsin infant deaths. The consistent higher neonatal mortality rate (NMR) raises not only a sense of critical awareness on racial/ethnic disparities in neonatal mortality, but also questions about potential mechanisms contributing to the discrepancy. This study assessed the impact of infant birthweight and prematurity on neonatal morality risks and disparities among racial/ethnic minorities in Wisconsin from 1991 through 2005. Linked birth/infant death data (singletons) were obtained from the Wisconsin Interactive Statistics on Health query system, and analyzed using multivariate log-linear regression modeling approaches. Results revealed that, although a large decrease in white NMRs was observed, neonatal mortality risks for blacks and Hispanics did not significantly change. This discord led to a widened racial/ethnic gap in NMRs. Substantial variations on neonatal mortality risks by birth weight and prematurity were found among whites, blacks, and Hispanics infants. Notably, among low birthweight and preterm infants, blacks and Hispanics appeared to have more favorable NMRs than whites. White infants had the lowest NMRs only delivered at full-term and about 2,500 grams. This study suggests that the variation of neonatal mortality risks may be linked to differences among racial/ethnic groups for birth weigh and prematurity. Appropriate policy interventions to reduce these racial/ethnic disparities in neonatal mortality should take into account not only birthweight/prematurity-specific mortality risks, but also NMR distributions within and between birthweight/prematurity categories.