It is the position of the Academy of Nutrition and Dietetics that all women of reproductive age receive education about maternal and fetal risks associated with prepregnancy obesity, excessive gestational weight gain, and significant postpartum weight retention, including potential benefits of lifestyle changes. Behavioral counseling to improve dietary intake and physical activity should be provided to overweight and obese women, beginning in the preconception period and continuing throughout pregnancy, for at least 12 to 18 months postpartum. Weight loss before pregnancy may improve fertility and reduce the risk of poor maternal-fetal outcomes, such as preterm birth, gestational diabetes, gestational hypertension, pre-eclampsia, assisted delivery, and select congenital anomalies. Lifestyle interventions that moderate gestational weight gain may reduce the risk of poor pregnancy outcomes, such as gestational diabetes, gestational hypertension, large for gestational age, and macrosomia, as well as lower the risk for significant postpartum retention. Postpartum interventions that promote healthy diet and physical activity behaviors may reduce postpartum weight retention and decrease obesity-related risks in subsequent pregnancies. Analysis of the evidence suggests that there is good evidence to support the role of diet, physical activity, and behavior changes in promoting optimal weight gain during pregnancy; however, there is currently a relative lack of evidence in other areas related to reproductive outcomes.