What is the recommended approach for managing deworming in pregnancy?

Management of Deworming in Pregnancy

Pregnant women in hookworm-endemic areas (prevalence ≥20%) should receive single-dose albendazole (400 mg) or mebendazole (500 mg) after the first trimester, as recommended by WHO guidelines. 1, 2

Timing of Treatment

First Trimester

• Defer anthelminthic treatment until after the first trimester to minimize any theoretical teratogenic concerns, though evidence suggests inadvertent first-trimester exposure carries no additional risk of adverse birth outcomes 2
• If a woman becomes pregnant while on albendazole for conditions like alveolar echinococcosis, treatment can be held during the first trimester with close monitoring (monthly ultrasound surveillance) 3

Second and Third Trimesters

• Administer single-dose albendazole (400 mg) or mebendazole (500 mg) after the first trimester in endemic areas where hookworm or Trichuris prevalence exceeds 20-30% 1, 2
• Treatment is safe and can be incorporated into routine antenatal care programs 1

Drug Selection and Dosing

Recommended Agents

• Mebendazole 500 mg single dose has been studied extensively in pregnancy with no increased risk of miscarriages, malformations, stillbirths, early neonatal deaths, or premature births 1
• Albendazole 400 mg single dose is equally acceptable, with systematic reviews showing no association with adverse birth outcomes even with first-trimester exposure 2
• Alternative agents include levamisole or pyrantel, though these are less commonly used 1

Spectrum of Coverage

• Standard single-dose regimens primarily target Ascaris lumbricoides, hookworm, and Trichuris trichiura 4
• Important caveat: Single-dose albendazole or mebendazole does not effectively treat other helminths (Hymenolepis nana, Strongyloides stercoralis, Enterobius vermicularis) or protozoan infections (Giardia, Entamoeba) that may be prevalent in the same populations 4

Indications for Treatment

Population-Based Approach

• Implement preventive chemotherapy in areas where soil-transmitted helminth endemicity is ≥20% 2
• No individual screening required; treat all pregnant women after first trimester in endemic areas 1

Potential Benefits

• Primary benefit is reduction of iron-deficiency anemia from hookworm-related blood loss 1
• Evidence for benefit is strongest in women with moderate to heavy hookworm infections 5
• No consistent effect demonstrated on birth weight, perinatal mortality, or congenital anomalies in areas with low infection intensity 5

Safety Profile

Maternal and Fetal Safety

• Large randomized controlled trials show no increased risk of adverse birth outcomes including miscarriages, malformations, stillbirths, or prematurity 1
• Systematic review of 46 studies found no evidence of harm from inadvertent first-trimester exposure 2
• No effect on perinatal mortality or congenital anomalies observed in trials 5

Postpartum Considerations

• Treatment can be safely restarted immediately postpartum 3
• For women requiring chronic albendazole therapy (e.g., echinococcosis), formula feeding may be preferred over breastfeeding due to concerns about infant drug exposure 3

Special Populations

Heavy Hookworm Infection

• Women with moderate to heavy hookworm burden may derive greater benefit from albendazole treatment for anemia prevention (OR 0.45 for anemia reduction) 5
• Consider this subgroup when prioritizing treatment resources 5

Chronic Parasitic Infections

• For serious infections like alveolar echinococcosis requiring long-term albendazole, hold treatment during first trimester with close monitoring (monthly imaging) 3
• Restart treatment if lesions enlarge or new lesions form 3
• Shared decision-making is essential given the balance between disease progression risk and theoretical drug concerns 3

Common Pitfalls to Avoid

• Do not withhold treatment after the first trimester in endemic areas based on unfounded teratogenicity concerns—the evidence strongly supports safety 1, 2
• Do not assume single-dose treatment addresses all intestinal parasites—protozoa and certain helminths require different regimens 4
• Do not rely solely on deworming to address maternal anemia—ensure routine provision of iron supplementation and malaria prophylaxis in appropriate settings 5
• Do not screen individual women for helminth infections before treatment in endemic areas—population-based preventive chemotherapy is more cost-effective 1