Santos S, et al. - The separate and combined associations of maternal pre-pregnancy body mass index (BMI) and gestational weight gain with the risks of pregnancy complications were investigated along with their population impact. In this individual participant data meta-analysis of 39 cohorts comprising 265,270 births, researchers identified higher risks of gestational hypertensive disorders, gestational diabetes, and large for gestational age at birth in correlation with higher maternal pre-pregnancy BMI and gestational weight gain, across their full ranges. The higher preterm birth risk was observed at lower and higher BMI and weight gain. Findings thereby support encouraging a healthy pre-pregnancy BMI and gestational weight gain in order to diminish the burden of pregnancy complications and ultimately the risk of maternal and neonatal morbidity.