The gastrointestinal tract undergoes many physiologic changes in pregnancy. With advancing gestation, increased levels of progesterone result in decreased smooth muscle activity. Esophageal motility, lower esophageal sphincter tone, as well as gastric tone and contractility are decreased during pregnancy. Small intestinal motility decreases significantly between the first and second trimesters, and remains fairly constant during the third trimester before returning to pre-pregnancy levels in the postpartum period. Biliary contractility is also similarly altered.

Heartburn occurs in nearly half of all pregnancies. It develops early in pregnancy and resolves in the postpartum period. A combination of decreased lower esophageal sphincter pressure and decreased gastric motility, with mechanical obstruction secondary to the gravid uterus, plays a contributing role. Clinical features of reflux, mainly heartburn and regurgitation, are similar to those in the nonpregnant patient. The evaluation of these complaints seldom requires more than an adequate history, although endoscopy may be a necessary method of evaluating more severe cases in pregnancy. Treatment of these symptoms in the pregnant patient consists primarily of nonpharmacologic interventions, reserving medication for refractory cases. Lifestyle changes such as elevation of the upper body while at rest, and decreasing activity that exacerbates symptoms should be prescribed. If these do not improve the patient’s symptoms, antacids may be taken before meals and at bedtime; sucralfate 1 g three times daily may be added. For severe cases, histamine blockers such as cimetidine or ranitidine may be used to alleviate symptoms. Symptoms associated with reflux resolve in most patients in the postpartum period.

Complaints of diarrhea in pregnancy should be investigated in the same manner as in the nonpregnant state. A careful history should be taken with focus on characteristics of present illness, diet, laxative use, and eating disorders. Acute microbial diarrhea usually is a self-limiting entity, resolving spontaneously within 24–72 hours, and is treated supportively with adequate hydration. If necessary, mild antidiarrheal agents such as kaolin and pectin may be prescribed. Stronger medications should be avoided as they may lead to bacterial overgrowth in the intestines. Care should be taken to ensure that adequate hydration is achieved to prevent preterm labor. For persistent diarrhea, stool culture and examination for ova and parasites should be undertaken and treatment is undertaken accordingly. Endoscopy is safe in pregnancy, and may be employed when necessary for the evaluation of persistent diarrhea.

Irritable bowel disease is a constellation of continuous and recurrent abdominal pain, which is relieved with defecation or associated with change in frequency or consistency of stool and/or disturbed defecation with no organic cause. It is a common disorder in the nonpregnant population, and it may often be encountered during pregnancy. Although the etiology is unknown, the decrease in gastrointestinal motility and pressure of the gravid uterus on the large bowel may aggravate symptoms of irritable bowel disease. Treatment of both irritable bowel disease and constipation is conservative. Increased water intake, frequent small meals, and a high-fiber diet are excellent first steps. Stool-bulking agents may be added if necessary, followed by emollient laxatives for more difficult cases.

Pregnancy-induced changes in symptoms from peptic ulcer disease may be mediated by a decrease in gastric acid secretion and an increase in mucus secretion. Clark reported that of over 300 women with known peptic ulcer disease, 44% had improvement in symptoms, and an additional 44% became asymptomatic. Pregnant women with symptoms of peptic ulcer disease often have their complaints ascribed to gastroesophageal reflux and are treated accordingly, which often improves ulcer symptomatology. Conventional antiulcer therapy, including antacids after meals and at bedtime, and sucralfate are usually sufficient to ameliorate symptoms encountered during pregnancy. Histamine receptor antagonists should be used if conservative management does not alleviate symptoms. If such measures do not improve patient symptoms, a search for Helicobacter pylori infection is indicated and if detected, antimicrobial treatment may be considered. For patients whose symptoms do not improve, or are associated with other “alarm” symptoms such as gastrointestinal bleeding or anemia, endoscopic examination should be undertaken. In the rare event that perforation or hemorrhage complicates ulcer disease, the patient should be managed surgically as in the nonpregnant state. For patients with symptoms that can be managed conservatively during pregnancy, curative surgical therapy should be reserved for the postpartum period.