The rapidly increasing rates of obesity among women of childbearing age, not only in the United States but also across the globe, contribute to increased risks during pregnancy and childbirth. Overweight and obesity are quantified by body mass index (BMI) for clinical purposes. In 2010, 31.9% of US women aged 20 to 39 years met the definition of obesity, a BMI of 30 kg/m2 or greater. Across the life span, obesity is associated with increased risks of hypertension, cardiovascular disease, diabetes, sleep apnea, and other diseases. During pregnancy, increasing levels of prepregnancy BMI are associated with increases in both maternal and fetal/neonatal risks. This article reviews current knowledge about obesity in pregnancy and health risks related to increased maternal BMI, addresses weight stigma as a barrier to care and interventions that have evidence of benefit, and discusses the development of policies and guidelines to improve care.