One third of adult women in the United States are obese. During pregnancy, obese women are at increased risk for several adverse perinatal outcomes, including anesthetic, perioperative, and other maternal and fetal complications. Obstetricians should provide preconception counselling and education about the possible complications and should encourage obese patients to undertake a weight reduction program before attempting pregnancy. Obstetricians also should address prenatal and peripartum care considerations that may be especially relevant for obese patients, including those who have undergone bariatric surgery.