Pregnancy outcome after gestational exposure to mebendazole: A prospective controlled cohort study

OBJECTIVE: Mebendazole is an anthelmintic that is commonly needed in women of reproductive age. Its use in pregnancy is a reason for concern for women and their health care providers. The purpose of this study was to examine the fetal safety of mebendazole. STUDY DESIGN: The Israeli Teratogen Information Service prospectively collected and followed 192 pregnancies exposed to mebendazole in pregnancy, 71.5% of whom had first-trimester exposure. Pregnancy outcome was compared with that of a matched control group, who were counseled for nonteratogenic exposure. RESULTS: There was no increase in the rate of major malformations between the groups (5/150 pregnancies [3.3%; mebendazole] vs 3/175 pregnancies [1.7%; nonteratogenic control subjects]; P = .478). There was a higher rate of elective terminations of pregnancy in the exposed group compared with the control group (22/192 pregnancies [11.5%; mebendazole] vs 3/192 pregnancies [1.6% [nonteratogenic control subjects]; P = .000). CONCLUSION: This study suggests that mebendazole does not represent a major teratogenic risk in humans when it is used in the doses that are used commonly for pinworm (Enterobius vermicularis) infestation.