Are preterm black infants larger than preterm white infants, or are they more misclassified?

Abstract

In birth certificate data for Massachusetts resident births from 1978 to 1982, 12-27% of births purportedly under 31 weeks of gestation were probably misclassified, i.e. had birthweight greater than or equal to 2500 g. Correcting for maldistribution of births removed 34% and 23%, respectively, of black and white births with reported gestational ages less than 36 weeks but with implausible weights. Percentages of unknown and incomplete reports of last menstrual period were also significantly higher for blacks. After adjustment, preterm black infants weighed less than whites at each gestational age. The proportion of infants less than 2500 g born at term (greater than or equal to 37 weeks gestation) was higher (although not significantly) among blacks. These findings are consistent with hypotheses that low socioeconomic status negatively affects the rate of intrauterine growth.

PIP: In birth certificate data for Massachusetts, US resident births from 1978 to 1982, 12 to 27% of births purportedly under 31 weeks of gestation were probably misclassified, i.e. had birthweight or = 2500 grams. Correcting for maldistribution of births removed 34% and 23%, respectively, of black and white births with reported gestational ages 36 weeks but with implausible weights. % of unknown and incomplete reports of last menstrual period were also significantly higher for blacks. After adjustment, preterm black infants weighed whites at each gestational age. The proportion of infants 2500 grams born at term ( or = 37 weeks gestations) was higher (although not significantly) among blacks. These findings are consistent with hypotheses that low socioeconomic status negatively affects the rate of intrauterine growth. Future studies of fetal growth patterns from birth certificate data should adjust for both probably misclassified birthweight and cases of implausible gestational ages. These adjusted cases should also be considered separately in terms of morbidity and mortality, as they may derive from different populations.