Santos S, et al. - Researchers performed individual participant data meta-analysis of 39 cohorts to examine how maternal pre-pregnancy body mass index (BMI) and gestational weight gain separately and in combination influence the risks of pregnancy complications and their population impact. Outcomes revealed risks of pregnancy complications in correlation with maternal pre-pregnancy BMI and gestational weight gain, across their full ranges. The highest risk of pregnancy complications was noted for obese mothers with high gestational weight gain. The burden of pregnancy complications could be reduced by promoting a healthy pre-pregnancy BMI and gestational weight gain that may ultimately reduce the risk of maternal and neonatal morbidity.