In the United States, more than one third of women are obese, more than one half of pregnant women are overweight or obese, and 8% of reproductive-aged women are extremely obese, putting them at a greater risk of pregnancy complications. Therefore, preconception assessment and counseling are strongly encouraged for obese women and should include the provision of specific information concerning the maternal and fetal risks of obesity in pregnancy, as well as encouragement to undertake a weight-reduction program. At the initial prenatal visit, height and weight should be recorded for all women to allow calculation of body mass index (calculated as weight in kilograms divided by height in meters squared), and recommendations for appropriate weight gain should be reviewed at the initial visit and periodically throughout pregnancy. Nutrition consultation should be offered to all overweight or obese women, and they should be encouraged to follow an exercise program. Pregnant women who have undergone bariatric surgery should be evaluated for nutritional deficiencies and the need for vitamin supplementation when indicated. Obese patients undergoing cesarean delivery may require thromboprophylaxis with pneumatic compression devices and unfractionated heparin or low molecular weight heparin. For all obese patients, anesthesiology consultation early in labor should be considered, and consultation with weight-reduction specialists before attempting another pregnancy should be encouraged.