The importance of extreme prematurity and low birthweight to US neonatal mortality patterns: implications for prenatal care and women's health.

OBJECTIVE

In order to frame the appropriateness of neonatal mortality reduction efforts that begin only after pregnancy is recognized, this study examined the relative contributions of different gestational age and birthweight groups to total neonatal mortality and to racial disparities in neonatal mortality in the United States.

METHODS

Using the national linked birth/infant death data set for the 1988 cohort, the relative contributions of different birthweight and gestational age groups to national neonatal mortality rates were calculated. The relative contributions of these groups to the racial disparity in neonatal mortality were also assessed.

RESULTS

Very low birthweight infants (< 1,500 g) accounted for 1.2% of all births, but 64.2% of all neonatal deaths. The very low birthweight rate for whites was 0.93%, while that for blacks was 2.79% with the contribution of this group to neonatal mortality higher for blacks than whites. Infants less than 1,000 g contributed more than 80% of the racial disparity in neonatal mortality.

CONCLUSION

Neonatal mortality patterns in the United States have become highly dependent on infants with gestational ages that approach the second trimester. Preventing neonatal mortality by enhancing care only after pregnancy has been recognized, therefore, may be limited. Strategies that link prenatal care to broader initiatives to improve the health of women regardless of pregnancy status may be more effective.