In this issue of Epidemiology, Chen et al report that obese mothers who gained the most weight during pregnancy had elevated risk for infant mortality. Other outcomes related to excess maternal weight or weight gain not only cause complications around the time of birth but also confer elevated chronic disease risk for both mother and child. There is good reason to believe that constraining gestational weight gain within an optimal range will minimize adverse outcomes. Revised gestational weight gain guidelines are needed, especially for obese women.