The effects of maternal weight gain patterns on term birth weight in African-American women

Objective. The goals of our study were (1) to estimate the trends in maternal weight gain patterns and (2) to estimate the influence of variation in maternal weight and rate of weight gain over different time periods in gestation on variation in birth weight in African-American and non-African-American gravidas. Study Design and Setting.Data from a prospective cohort study in which pregnant women were monitored at multiple time points during pregnancy were analysed. Maternal weight was measured at three times during pregnancy: preconception (W₀); 16-20 weeks gestation (W₁); 30-36 weeks gestation (W₂), in a cohort of 435 women with full-term singleton pregnancies. The relationship between gestational age-adjusted birth weight (aBW) and measures of maternal weight and rate of weight gain across pregnancy was estimated using a multivariable longitudinal regression analysis stratified on African-American race. Results. The aBW was significantly associated with maternal weight measured at any visit in both strata. For African-American women, variation in aBW was significantly associated with variation in the rate of maternal weight gain in the first half of pregnancy (W₀₁) but not the rate of maternal weight gain in the second half of pregnancy (W₁₂); while for non-African-American women, variation in aBW was significantly associated with W₁₂ but not W₀₁. Conclusion. Factors influencing the relationship between aBW and maternal weight gain patterns depend on the context of the pregnancy defined by race. Clinical decisions and recommendations about maternal weight and weight gain during pregnancy may need to account for such heterogeneity.