Pregnancy is associated with a wide range of physiologic alterations in many organ systems throughout the body. Perturbations of gastrointestinal motility are common during pregnancy and may result in a variety of symptom complexes, including heartburn, nausea and vomiting, right upper quadrant discomfort, constipation, and diarrhea. Minor constipation and diarrhea in pregnancy are often treated by the patient herself, her obstetrician, or her primary care physician; on occasion, the patient may be referred to a gastroenterologist. Familiarity both with the causes of constipation and diarrhea in pregnancy and with an approach to evaluating and treating these disorders in nonpregnant patients is important to physicians involved in the care of the pregnant patient. The incidence, pathogenesis, evaluation, and treatment of constipation and diarrhea in pregnancy are reviewed in this article.