Badon SE, Quesenberry CP, Xu F, et al. - In the present study, the researchers sought to evaluate correlations of gestational weight gain (GWG) according to the Institute of Medicine recommendations with birthweight and obesity at age 3 years, utilizing conventional analyses comparing outcomes between mothers and sibling analyses contrasting outcomes within mothers, which control for stable within-family unmeasured confounders like familial environment and genetics. Ninety-six thousand two hundred eighty-nine women with live births were identified in 2008–2014 at Kaiser Permanente Northern California. Findings suggested that GWG possibly has a direct effect on birthweight, however, shared environmental and lifestyle factors within families might play a greater role in determining early-childhood weight status and risk of obesity than GWG.