Evidence about vaccine safety during pregnancy usually derives from Pregnancy Registry data. Phase III clinical trials of the quadrivalent vaccine targeting human papillomavirus (HPV) 6/11/16/18 were performed predominantly in reproductive aged women, some of whom became pregnant during the trials. This report by Garland and colleagues compares maternal, fetal and neonatal outcomes in vaccine and placebo recipients from 5 clinical trials. An accompanying article by Dana and colleagues1 reports pregnancy outcomes from the first 2 years of the Pregnancy Registry monitoring post-marketing exposures to the quadrivalent HPV vaccine. Although the clinical trials were not powered to assess safety in pregnancy, the paper by Garland provides a valuable insight. The strengths of this study are the large numbers of pregnancies analysed, the prospective and thorough documentation of outcomes, and the availability of data from a placebo group; these features overcome the shortcomings of registry data.

This analysis reports combined data …