Gastrointestinal Changes in Pregnancy

Pregnancy changes gastrointestinal function through several interacting mechanisms rather than one isolated “pregnancy hormone” effect. Rising progesterone relaxes smooth muscle, lowers resting lower esophageal sphincter tone, slows gastric emptying, and prolongs small-bowel transit. Circulating motilin also falls. The enlarging uterus raises intra-abdominal and intragastric pressure, particularly later in pregnancy. Delayed emptying, increased pressure, and a weaker antireflux barrier produce heartburn and regurgitation; increased gastric acid production is not the primary explanation. The same slower transit contributes to constipation. The colon absorbs more water and sodium, the gravid uterus adds mechanical pressure, and oral iron can further harden stools. A patient taking a recommended prenatal iron supplement may therefore develop constipation even when her diet has not changed. Oral changes can accompany these adaptations. Gingival hyperemia and hypertrophy make bleeding gums more likely, while excessive salivation, or ptyalism, can intensify nausea. Sugar-free gum, careful oral hygiene, and frequent small sips of water may reduce the distress caused by ptyalism. These changes are common, but “common in pregnancy” does not mean every gastrointestinal symptom is benign. Timing, severity, hydration, pain location, associated...