What medications are safe for treating constipation in pregnant women?

Safe Medications for Constipation in Pregnant Women

For pregnant women with constipation, start with dietary fiber (30 g/day), then escalate to polyethylene glycol (PEG) or lactulose as first-line pharmacological therapy, reserving stimulant laxatives like bisacodyl for short-term use only when other options fail. 1

Treatment Algorithm

Step 1: Dietary Modifications (First-Line)

• Increase dietary fiber intake to approximately 30 g/day through fruits, vegetables, whole grains, and legumes 1, 2
• Ensure adequate fluid intake, particularly water, to soften stools and improve transit time 2, 3
• Aim for 3-4 servings of fruits and 3-4 servings of vegetables daily 2
• Specific high-fiber foods include prunes, raisins, apples, pears, broccoli, leafy greens, sweet potatoes, and legumes 2

Step 2: Bulk-Forming Agents (If Dietary Changes Ineffective After 1 Week)

• Psyllium husk (Metamucil) or methylcellulose are safe during pregnancy due to minimal systemic absorption 1, 3
• These agents improve stool viscosity and transit time while increasing bulk 2
• Note that excessive fiber can cause maternal bloating 2

Step 3: Osmotic Laxatives (If Bulk-Forming Agents Fail After 1-2 Weeks)

• Polyethylene glycol (PEG) 17g daily can be safely administered during pregnancy 1, 3, 4
• Lactulose is also safe but may cause more bloating than PEG 1, 3, 5
• Lactulose is pregnancy category B with reproduction studies showing no evidence of harm to the fetus 5
• Magnesium hydroxide at 400-500 mg daily is considered safe and effective 3
• These osmotic laxatives should be used short-term to avoid dehydration or electrolyte imbalances 6

Step 4: Stimulant Laxatives (Use Cautiously, Short-Term Only)

• Stimulant laxatives should generally be avoided as routine therapy but can be used cautiously for short-term relief when other methods fail 1, 2, 3
• Bisacodyl 5-10 mg daily or senna can be considered for refractory cases 3, 7
• Safety data are conflicting, but these have been used extensively without clear evidence of harm 3
• The main concern is tenesmus potentially triggering preterm contractions, particularly in the third trimester 3
• The second trimester offers the safest window for more aggressive management since organogenesis is complete 3

Important Clinical Considerations

Evaluation Components

• Assess frequency and consistency of bowel movements 1
• Evaluate for pain or bleeding during defecation 1
• Screen for hemorrhoids, which occur in approximately 80% of pregnant women, especially in the third trimester due to compression from the gravid uterus 1, 2
• Evaluate for secondary causes including hypothyroidism, hypercalcemia, and iron supplementation effects 3

Management of Associated Hemorrhoids

• Hydrocortisone foam has been shown to be safe in the third trimester for symptomatic relief 2, 3
• Stool softeners (PEG) can help achieve softer stools and reduce strain on hemorrhoids 8

Common Pitfalls to Avoid

• Do not use stimulant laxatives routinely or long-term - reserve for refractory cases only 1, 2
• Avoid excessive fiber supplementation which can worsen bloating 2
• Be cautious with osmotic and stimulant laxatives to prevent dehydration or electrolyte imbalances in pregnant women 6
• Do not use other laxatives during initial therapy as loose stools may falsely suggest adequate treatment 5

Prevalence and Pathophysiology

• Constipation affects approximately 20-40% of pregnant women 1, 2
• Primary cause is increased progesterone levels slowing GI motility 1
• Contributing factors include hormonal changes, medications (especially iron supplements), anatomic compression from the gravid uterus, and low dietary fiber intake 1, 2

Safety Profile Summary

• PEG and lactulose are the safest pharmacological options with minimal systemic absorption 1, 3, 5
• Bulk-forming agents like psyllium have minimal systemic absorption and are not expected to cause congenital anomalies 1, 6
• Stimulant laxatives have been used extensively but should be limited to short-term use due to theoretical concerns about uterine stimulation 3, 7