PURPOSE: To review the pathophysiology of gastrointestinal motility disorders during pregnancy, their clinical manifestations, and their management. DATA SOURCES: Studies published from 1963 to 1992 identified by computerized literature searches of Index Medicus and MEDLINE; hand searches; contact with pharmaceutical representatives for information on drug therapy during pregnancy; and selected texts on drugs and obstetrics. STUDY SELECTION: Selected studies were those involving controlled design of physiology related to pregnancy or to hormonal effects on the gastrointestinal tract or both, and clinical studies or previous reviews that contributed to the understanding of the gastrointestinal effects of pregnancy. DATA EXTRACTION: Data concerning the epidemiology, causes, clinical manifestations, and complications of altered gastrointestinal motility during pregnancy as well as the strength of association between gastrointestinal disorders of pregnancy and hormonal changes were evaluated and used to develop a practical approach to evaluate and manage these patients. RESULTS OF DATA SYNTHESIS: Effects on the gastrointestinal tract during pregnancy are caused primarily by hormonal changes and not the physical effects of the gravid uterus. Motility changes occur throughout the gastrointestinal tract, including a reduction in lower esophageal sphincter pressure and its physiologic function with resulting gastroesophageal reflux and the risk for aspiration; alterations in gastric motor function associated with nausea and vomiting; and a decrease in the rate of small-bowel and colonic transit manifested primarily as abdominal bloating and constipation. These effects are mediated by progesterone, with estrogen probably acting as a primer. CONCLUSIONS: Given the large number of pregnancies each year complicated by gastrointestinal motility disorders, many physicians (including internists and gastroenterologists) must manage these problems. Knowledge of the underlying physiologic alterations in gastrointestinal motility during pregnancy and of safe treatment options is essential to the care of the pregnant patient.