Pregnancy outcome following exposure to permethrin and use of teratogen information

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 questionaire, 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.