Obesity, race/ethnicity and birth weight

We sought to investigate the relationship between maternal obesity expressed in body mass index (BMI), race/ethnicity and birth weight to determine if there was a difference between black non-hispanic (BNH) and white non-hispanic (WNH) populations. In a retrospective cohort study of a large urban hospital's deliveries from 1990 to 2003, we analyzed nondiabetic, nonhypertensive, nonsmoking/non-substance abusing women with uncomplicated, normal spontaneous vaginal deliveries at 37 or more weeks gestation. We compared the average birth weight between BNH and WNH in 5 maternal prepregnancy BMI categories. For the WNH population, birth weight generally increased with increasing prepregnancy BMI. In contrast, when we analyzed the BNH population, as the maternal prepregnancy BMI increased, the birth weight decreased. In addition, in every prepregnancy BMI category, the WNH had a larger average birth weight than BNH. In our population there was an association between prepregnancy maternal BMI and birth weight that was dependent on race/ethnicity. In the WNH population, women with high prepregnancy BMI had larger babies. However, in the BNH women, there was an inverse relationship between prepregnancy BMI and birth weight such that the most obese women had significantly smaller babies on average. We speculate that factors such as environment, nutrition and genetics may contribute to this difference in birth weight between BNH and WNH populations.Tabled 1BMIRaceTotal #Birth weight (g)P value<20BNH3662942< .05WNH880324020-24.9BNH12792994< .05WNH2353331125-29.9BNH7273036< .05WNH468333130-39.9BNH4353126< .05WNH1363277>40BNH912846< .05WNH143514 Open table in a new tab