Safety of benzyl benzoate lotion and permethrin in pregnancy: a retrospective matched cohort study

Objective  To assess the safety of benzyl benzoate lotion (BBL) and permethrin, topical treatments for scabies, during pregnancy.Design  A retrospective controlled cohort study.Population  Refugee and migrant women attending antenatal clinics (ANC) on the Thai–Burmese border between August 1993 and April 2006.Methods  Women treated with either BBL (25%) or permethrin (4%) were identified from a manual search of antenatal records. Each case of scabies was matched with four scabies‐free controls for gravidity, age, smoking status, malaria, period of treatment and gestational age at treatment. Conditional Poisson regression was used to estimate risk ratios for outcomes of pregnancy (proportion of abortions, congenital abnormalities, neonatal deaths, stillbirths and premature babies), mean birthweight and estimated median gestational age, for scabies and scabies‐free women, independently for BBL and permethrin.Results  There were no statistically significant differences in pregnancy outcomes between women who were treated with either BBL (n= 444) compared with their matched controls (n= 1,776) or permethrin (n= 196) treated women and their matched controls (n= 784). Overall, only 10.9% (n= 66) of treatments were in the first trimester. Retreatment rates were higher with BBL 16.4%, than permethrin 9.7%, P= 0.038. Scabies was more common during cooler periods.Conclusion  We found no evidence of adverse effects on pregnancy outcome due to topical 25% BBL or 4% permethrin.