Ukah UV, Bayrampour H, Sabr Y., et al. - Researchers sought to evaluate the correlation between suboptimal gestational weight gain and severe adverse birth outcomes by pre-pregnancy body mass index (BMI) categories, including obesity class I to III. They performed a population-based study of pregnant women with singleton hospital births in Washington State, US, between 2004 and 2013. They estimated optimal, low, and excess weight gain in each BMI category based on weight gain by gestational age as recommended by the American College of Obstetricians and Gynecologists and the Institute of Medicine. They recruited a sum of 722,839 women with information on pre-pregnancy BMI. They noted, during pregnancy, most women do not achieve optimal weight gain. The results showed that low weight gain was correlated with improved risk of severe adverse birth outcomes, and in particular with maternal death and perinatal death. An association was found between excess gestational weight gain and severe adverse birth outcomes, except for women who were overweight prior to pregnancy. They found that low weight gain may potentially be applied as a marker of elevated risk of stillbirth; nevertheless, additional studies are required to evaluate such utility.