Treatment of Constipation in Pregnancy
Start with dietary fiber (30 g/day) and adequate fluids, then escalate to polyethylene glycol (PEG) 17g daily as first-line pharmacological therapy if dietary measures fail after one week. 1, 2, 3
Initial Non-Pharmacological Management
Increase dietary fiber to approximately 30 g/day through fruits, vegetables, whole grains, and legumes—aim for 3-4 servings of fruits and 3-4 servings of vegetables daily. 1, 2, 3
Ensure adequate fluid intake, particularly water, to soften stools and improve bowel transit time. 1, 2, 3
Encourage pregnant women to avoid straining during bowel movements by providing ample time and using relaxation techniques. 1, 3
Pharmacological Treatment Algorithm
First-Line Pharmacological Therapy
Polyethylene glycol (PEG) 17g daily is the preferred first-line agent if dietary changes fail after 1 week. 2, 3 PEG is safe during pregnancy due to lack of systemic absorption and has fewer side effects than alternatives. 1
Bulk-forming agents (psyllium husk or methylcellulose) are safe alternatives due to lack of systemic absorption. 1 Soluble fiber like psyllium improves stool viscosity and transit time more effectively than insoluble fiber. 1
Second-Line Options
Lactulose is safe but may cause more maternal bloating than PEG, so it should be considered on a case-by-case basis. 1, 2, 3
Magnesium hydroxide 400-500 mg daily is safe and effective but should be used cautiously in patients with renal impairment due to risk of hypermagnesemia. 2, 3
Immediate Relief for Severe Discomfort
- Glycerin suppository may be considered for immediate relief if the patient is severely uncomfortable. 2
Management of Associated Hemorrhoids
Approximately 80% of pregnant women develop hemorrhoids, particularly in the third trimester due to compression of the rectum by the gravid uterus. 1, 3
Hydrocortisone foam is safe in the third trimester for symptomatic relief—a prospective study of 204 patients showed no adverse events compared with placebo. 1, 2, 3
Critical Pitfalls to Avoid
Avoid stimulant laxatives (including senna) because safety data during pregnancy are conflicting. 1 While one Cochrane review found stimulant laxatives effective 4, the most recent 2024 AGA guidelines recommend against them due to safety concerns. 1
Do not use bulk laxatives for opioid-induced constipation if the patient is on pain medications. 2, 3
Enemas are contraindicated in patients with recent colorectal/gynecological surgery, recent anal trauma, or recent pelvic radiotherapy. 2, 3
Magnesium salts should be used cautiously in renal impairment due to risk of hypermagnesemia. 2, 3
When to Hospitalize
Severe dehydration or inability to tolerate oral intake requires hospitalization for IV fluid replacement. 2, 3
Implement anticoagulant thromboprophylaxis during hospital stay to prevent venous thromboembolism. 2, 3
Monitoring and Follow-Up
Reassess bowel movement frequency and consistency after initiating treatment, with a goal of achieving soft, formed stools every 1-2 days. 2, 3
Adjust treatment based on response, escalating through the algorithm as needed. 2, 3
Evaluate for secondary causes including hypothyroidism, hypercalcemia, and iron supplementation effects if constipation is refractory to treatment. 3
Understanding the Pathophysiology
Constipation affects 20-40% of pregnant women and results from multiple factors: increased progesterone levels slow GI motility, anatomic changes from the gravid uterus compress the rectum, and medications (particularly iron supplements) contribute to symptoms. 1 This understanding helps explain why a stepwise approach starting with dietary measures is both physiologically sound and evidence-based.