What are the appropriate anti-constipation medications for pregnant women?

Management of Constipation During Pregnancy

For pregnant women with constipation, first-line treatment includes dietary fiber, adequate fluid intake, and when needed, bulk-forming agents or osmotic laxatives such as polyethylene glycol or lactulose, which can be safely administered during pregnancy. 1

Prevalence and Causes

• Constipation affects approximately 20-40% of pregnant women 1
• Primary causes include:
  • Increased progesterone levels slowing GI motility 1
  • Hormonal, medication-related, and physiological changes 1
  • Mechanical compression from the gravid uterus, especially in the third trimester 1
  • Low dietary fiber intake during pregnancy 1

Evaluation

• Detailed history regarding frequency and consistency of bowel movements 1
• Assessment of pain or bleeding during bowel movements 1
• Evaluation of symptom severity 1
• Screening for hemorrhoids, which occur in approximately 80% of pregnant women 1

Treatment Algorithm

Step 1: Non-Pharmacological Approaches

• Increase dietary fiber intake to approximately 30 g/day (fruits, vegetables, whole grains, legumes) 1
• Ensure adequate fluid intake, particularly water, to soften stools 1
• Encourage regular physical activity if appropriate 2, 3
• Allow sufficient time for bowel movements and use relaxation techniques 1

Step 2: Bulk-Forming Agents

• Psyllium husk or methylcellulose are safe during pregnancy due to minimal systemic absorption 1
• Soluble fiber (psyllium) improves stool viscosity and transit time while increasing bulk 1
• Note that excessive fiber can cause maternal bloating 1

Step 3: Osmotic Laxatives

• Polyethylene glycol (PEG) can be safely administered during pregnancy 1, 4
• Lactulose is also safe but may cause more bloating than PEG 1, 4
• Short-term use is recommended to avoid dehydration or electrolyte imbalances 2, 5

Step 4: Other Options (with caution)

• Stool softeners like docusate sodium may be considered 2, 4
• Stimulant laxatives should generally be avoided as safety data are conflicting 1
• If necessary, bisacodyl or sodium picosulfate may be considered in the second and third trimesters as second-line treatment 4

Special Considerations

• For hemorrhoids associated with constipation, hydrocortisone foam has been shown to be safe in the third trimester 1
• Most laxatives have minimal systemic absorption and are not expected to increase risk of congenital anomalies 2
• Macrogol (PEG) may have advantages over lactulose including faster onset of action and fewer flatulence issues 4
• Women with pre-existing constipation may experience worsening symptoms during pregnancy and require more aggressive management 3, 6

Cautions and Contraindications

• Stimulant laxatives should be used cautiously and only for short-term relief 1, 2
• Excessive use of osmotic laxatives can lead to dehydration and electrolyte imbalances 2, 5
• Tenesmus associated with certain laxatives may be concerning in pregnancy due to potential association with preterm births 4
• Always weigh the benefits of pharmacologic treatment against possible adverse effects 5