Synopsis: In this protocol, Dr. Catalano reviews the pathophysiology, diagnosis, prevention, and treatment of obesity in pregnancy. Included are guidelines for avoiding obesity-related complications in pregnancy, notes on postpartum follow-up, and a list of seminal reports in this subject area. As the author notes, pregnancy offers a woman the unique opportunity to affect her long-term health and that of her offspring. The ultimate treatment of obesity during pregnancy lies in preventing further weight gain. This can be achieved by avoiding excessive weight gain during pregnancy and implementing lifestyle measures to attain a more normal body mass index (BMI) prior to the next pregnancy. Based on preliminary evidence, achieving these measures also may have both short- and long-term benefits for the offspring.