The Effect of Obesity and Pregnancy Weight Gain on Maternal and Child Health

In this study, we estimate the effect of prepregnancy obesity and excessive pregnancy weight gain on infant and maternal health outcomes. We rely on a large sample of maternally linked restricted data from 2004 to 2019 South Carolina birth certificates, which allow us to track the same mothers during multiple pregnancies over a period of more than 15 years. To address possible limitations of previous research, we account for genetic confounders and unobservable maternal and environmental factors by relying on a maternal fixed effects strategy. We find that gaining above recommended amounts of weight increases the likelihood of delivering a high weight infant by 2.34 percentage points, while being obese increases this likelihood by 2.58 percentage points. These large negative effects of weight gain outside recommended ranges, as well as the effects of being obese, are present in White and Black mothers. Also, our results indicate that mothers who gained too much weight, or were obese, had a higher likelihood of cesarean section and higher likelihood of being induced. Finally, among the subsample of Medicaid mothers, excessive pregnancy weight gain as well as inadequate weight gain increased the likelihood of NICU admission.