Maternal obesity is inextricably linked to adverse health outcomes for the mother and her children. The peripartum period is a critical period of risk. In this chapter, we examine the importance of maternal prepregnancy weight status, gestational weight gain, breastfeeding, and postpartum weight loss in relation to subsequent risk for maternal obesity and obesity in the offspring. Promoting optimal maternal weight during the preconception, pregnancy, and postpartum periods will provide lifelong benefits for maternal health and the health of her progeny.