Bivalent HPV Vaccine and Pregnancy: Reassuring Findings

Anna Wald, MD, MPH reviewing Panagiotou OA et al. BMJ 2015 Sep 7.

Miscarriage rates were not higher among immunized women, even if conception occurred within 90 days of vaccination.

Prior pooled studies of the bivalent human papillomavirus (HPV) vaccine showed a slightly increased risk for miscarriage among women who became pregnant within 90 days of immunization. Now, investigators have analyzed extended trial follow-up (goal, 6 additional years) supplemented by observation of an unvaccinated cohort. In the trial, women received either HPV vaccine or hepatitis A vaccine; after 4 years, those women randomized to hepatitis A vaccine also received HPV vaccine

Among 3394 pregnancies in HPV vaccinated women, 13.3% ended in miscarriage. In the subset of 381 pregnancies conceived within 90 days of immunization, the miscarriage rate was 13.1%. Among unvaccinated women, 12.8% miscarried (P=0.29). These results were unchanged after adjustment for age at conception or at vaccination, or calendar year. In the analyses that assessed risk for miscarriage of pregnancies conceived at any time after HPV vaccination, relative risk for miscarriage at 13 to 20 weeks' gestation among HPV vaccinated women was 1.35 (P=0.017) compared with all unexposed pregnancies. This increase in risk emerged only in comparison with women who received hepatitis A vaccine; no such increase was seen in comparison with unvaccinated women in the observational cohort.

Citation(s):

Panagiotou OA et al. Effect of bivalent human papillomavirus vaccination on pregnancy outcomes: Long term observational follow-up in the Costa Rica HPV Vaccine Trial. BMJ 2015 Sep 7; 351:h4358.