Effect of mebendazole therapy during pregnancy on birth outcome

Background In areas endemic for hookworm, routine antenatal mebendazole therapy could greatly reduce the prevalence of anaemia in pregnancy. At present, however, this is not a widely accepted control strategy because of a lack of data on the safety of the drug. We assessed the effect of mebendazole therapy during pregnancy on birth outcome. Methods A cross-sectional study was done in Sri Lanka, where prescription of mebendazole to women in the second trimester of pregnancy is recommended. Two hospitals were chosen for the study, and women who gave birth there between May, 1996, and March, 1997, were recruited. We compared the rates of major congenital defects, stillbirth, perinatal death, and low birthweight (≤1500 g) among babies of mothers who had taken mebendazole during pregnancy with those whose mothers had not taken an anthelmintic (controls). Findings The rate of major congenital defects was not significantly higher in the mebendazole group than in the control group (97 [1·8%] of 5275 vs 26 [1·5%] of 1737; odds ratio 1·24 [95% CI 0·8–1·91], p=0·39). Among 407 women who had taken mebendazole in the first trimester (contrary to medical advice), 10 (2·5%) had major congenital defects (odds ratio vs controls 1·66 [0·81–3·56], p=0·23). The proportions of stillbirths and perinatal deaths were significantly lower in the mebendazole group (1·9 vs 3·3%, 0·55 [95% CI 0·4–0·77]), as was the proportion of low-birthweight babies (1·1 vs 2·3%, 0·47 [95% CI 0·32–0·71]). Interpretation Mebendazole therapy during pregnancy is not associated with a significant increase in major congenital defects, but our results indicate that it should be avoided during the first trimester. This therapy could offer beneficial effects to pregnant women in developing countries, where intestinal helminthiases are endemic.