Pregnancy Outcome Following Exposure to Permethrin and Use of Teratogen Information

Abstract

NIX is a 1% permethrin creme rinse used for the treatment of head lice. There are no studies regarding human exposure during pregnancy. The primary objective of this study was to examine the safety of permethrin exposure during pregnancy. The secondary objective was to examine how teratogen information is perceived and used by women who requested information regarding this product. Women who had called the Motherisk and MotherSafe Programs to inquire about exposure to permethrin during pregnancy were followed-up to ascertain the outcome of their pregnancies. These women were compared with another group who had not been exposed to any known teratogenic drugs. Women who decided not to use permethrin were administered an additional questionnaire. We enrolled 147 women and completed outcomes on 113 pregnancies of women who had used permethrin some time during their pregnancy. There were 106 live births, six spontaneous abortions, one therapeutic abortion, and one major malformation in the women who used permethrin in the first trimester. The mean birthweight was 3540 +/- 492 g and the mean gestational age was 40 +/- 1 weeks. There were no statistically significant differences between the exposed and comparison groups in any of the pregnancy outcomes. Of the 34 women who chose not to use permethrin and who completed the additional questionnaire, 18 (52%) did not use permethrin because they did not feel the information was sufficiently reassuring. The results of this study suggest that the use of permethrin products during pregnancy appears to be relatively safe because there was no increase in the rates of major malformations. We also found that some women will not use a product during pregnancy unless they can receive a 100% guarantee that it will not harm their baby.

Association of pesticide exposure with human congenital abnormalities

“…Many studies have reported no increased risk of CAs in offspring residing in areas with pesticide use (de Siqueira et al, 2010; Marshall et al, 1997). Potential association between permethrin/benzyl benzoate lotion during pregnancy for therapeutic reasons (headlice and/or scabies treatment) and CAs was investigated in one study (Kennedy et al, 2005) concluding that no association exists and thus these pesticides are safe. However, the main limitation of this study was the small number of exposed women during the first trimester of pregnancy, when the child is more susceptible to developmental CAs (Kennedy et al, 2005).…”

“…Potential association between permethrin/benzyl benzoate lotion during pregnancy for therapeutic reasons (headlice and/or scabies treatment) and CAs was investigated in one study (Kennedy et al, 2005) concluding that no association exists and thus these pesticides are safe. However, the main limitation of this study was the small number of exposed women during the first trimester of pregnancy, when the child is more susceptible to developmental CAs (Kennedy et al, 2005). An exposure-dependent positive link between maternal residence in near toxic waste sites in New York state and CAs and an increased risk for MSAs (OR = 1.2, 95%C = 1.05–1.38) and pesticide exposure was reported (Geschwind et al, 1992) but these results could not be replicated in a following study done in California (Croen et al, 1997).…”

Skin infections in pregnancy

“…In a prospective study of 113 pregnant women, who were A C C E P T E D M A N U S C R I P T exposed to permethrin (31 during the 1 st trimester), no differences in live births, spontaneous abortions, major malformations, birth weight, and gestational age at delivery were observed when compared to matched controls. 77 This was supported in a study of 196 pregnant women exposed to permethrin. 78 Precipitated sulfur and benzyl benzoate 25% lotion are second-line treatments; however, they are less effective than permethrin.…”

Dermatological medications and local therapeutics

“…Due to its long-term effect, it is considered more effective than pyrethrum for lice infestation, although there are no comparative studies available on the two substances. The prospective study of 113 pregnant women who used permethrin shampoo (31 in the first trimester) gave no indication of an embryotoxic risk (Kennedy 2005). Mytton (2007) also found nothing remarkable among 196 pregnant women treated with permethrin.…”