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Updated analysis of pregnancy outcomes in the Costa Rica Vaccine Trial (CVT) and the long-term follow-up

Tuesday, September 23, 2014 — Poster Session III

12:00 p.m. – 2:00 p.m.

FAES Academic Center



* FARE Award Winner


  • OA Panagiotou
  • B Befano
  • P Gonzalez
  • C Porras
  • AC Rodriguez
  • R Herrero
  • M Schiffman
  • AR Kreimer
  • A Hildesheim
  • A Wilcox


Background: Previous studies could not rule out a small effect of vaccination with the bivalent human papillomavirus (HPV) vaccine (Cervarix) on risk of miscarriage in pregnancies conceived within 89 days. Methods: We analyzed data from the randomized and the long-term follow-up phases of the Costa Rica Vaccine Trial (CVT) and an unvaccinated control group in the same population. The unit of analysis is pregnancy. Exposed pregnancies were those conceived within 89 days of Cervarix vaccination at enrollment in CVT or at crossover of the women not originally randomized to Cervarix. Unexposed pregnancies were conceived at any time since control vaccination and by women in the unvaccinated control group. Results: Among 3,394 exposed and 3,227 unexposed pregnancies, 451 (13.3%) and 414 (12.8%), respectively, ended in miscarriage. The relative risks of miscarriage ranged from 1.02 (95% confidence intervals, CI, 0.78-1.34; P=0.87) in unadjusted analyses to 1.15 (95% CI, 0.86-1.54; P=0.34), when adjusting for the year of vaccination. Results were similar when we accounted for maternal age at conception or gestational age at miscarriage. Conclusion: The data do not support an effect of HPV vaccination on miscarriage risk.

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