Which of the following gastrointestinal changes is typically attributed to the relaxation of the lower esophageal sphincter by progesterone?

Heartburn (pyrosis)occurs in pregnancy mainly due to progesterone-induced relaxationof the lower esophageal sphincter. This hormone lowers smooth muscle tone, allowing gastric acid to reflux into the esophagus. Symptoms include burning sensation behind the sternum, worsened after meals or lying down. Normal lower esophageal sphincter pressure ranges between 10–30 mmHg, but pregnancy reduces it to below 10 mmHg. Risk factors include increased intra-abdominal pressure from the enlarging uterus and delayed gastric emptying. Complications include esophagitis and sleep disturbance.

Rationale for correct answer

3.The presence of heartburn (pyrosis) in pregnancy is directly linked to progesterone’s smooth muscle relaxation, causing reduced lower esophageal sphincter tone and gastric acid reflux. The clinical presentation is a burning retrosternal discomfort, especially worsened after meals or lying supine. This directly aligns with the pathophysiology described.

Rationale for incorrect answers

1.Pica is an abnormal craving for non-nutritive substances like clay or ice. It is associated with iron deficiency anemia, not progesterone-induced smooth muscle relaxation. Its pathophysiology relates to altered dopamine pathways and iron metabolism, not gastrointestinal sphincter tone.

2.Constipation is common in pregnancy but results from decreased intestinal peristalsis due to progesterone and increased water absorption in the colon. It is not caused by relaxation of the lower esophageal sphincter but rather delayed transit time within the intestines.

4.Gingivitis in pregnancy is due to vascular changes and exaggerated inflammatory response to dental plaque under high estrogen and progesterone levels. It involves gum swelling, bleeding, and hyperemia, not esophageal sphincter relaxation.

Take home points

• Progesterone lowers lower esophageal sphincter pressure, leading to gastroesophageal reflux and heartburn.

• Constipation in pregnancy results from delayed intestinal transit, not sphincter relaxation.

• Gingivitis is hormonally mediated gum inflammation, unrelated to esophageal sphincter physiology.

• Pica is associated with iron deficiency anemia, not gastrointestinal smooth muscle tone changes.

Heartburn in pregnancyis caused by progesterone-induced relaxationof the lower esophageal sphincterand increased intra-abdominal pressurefrom the enlarging uterus. Gastric acid reflux produces a burning retrosternal sensation. Normal gastric pH is 1.5–3.5, and when acid refluxes into the esophagus, mucosal irritation occurs. Risk factors include recumbency after meals, consumption of fatty or spicy foods, and delayed gastric emptying. Non-pharmacological interventions are first-line, with emphasis on dietary modifications and positional therapy to reduce acid exposure to the esophagus.

Rationale for correct answer

3.Consuming small, frequent meals reduces gastric volume, minimizing reflux into the esophagus. Smaller meals decrease gastric distension, lowering the pressure gradient across the lower esophageal sphincter and reducing the likelihood of acid regurgitation.

Rationale for incorrect answers

1.Increasing consumption of spicy foods exacerbates gastric acid secretion and directly irritates the esophageal mucosa, worsening heartburn symptoms. It increases mucosal sensitivity and reflux episodes rather than preventing them.

2.Eating large, infrequent meals distends the stomach, raising intragastric pressure and facilitating reflux through the weakened sphincter. This directly opposes recommended management.

4.Lying flat after eating increases the likelihood of acid reflux due to gravitational loss of barrier protection. The horizontal position facilitates acid movement from the stomach into the esophagus, worsening symptoms.

Take home points

• Heartburn in pregnancy results from progesterone-induced lower esophageal sphincter relaxation.

• Small, frequent meals are the best dietary modification to reduce reflux symptoms.

• Large meals, spicy foods, and lying flat exacerbate gastric reflux.

• Lifestyle changes precede pharmacologic interventions in management.