title: Quadrivalent HPV Vaccination and the Risk of Adverse Pregnancy Outcomes.
abstract: The quadrivalent human papillomavirus (HPV) vaccine is recommended for all girls and women 9 to 26 years of age. Some women will have inadvertent exposure to vaccination during early pregnancy, but few data exist regarding the safety of the quadrivalent HPV vaccine in this context.
  
  
  
  We assessed a cohort that included all the women in Denmark who had a pregnancy ending between October 1, 2006, and November 30, 2013. Using nationwide registers, we linked information on vaccination, adverse pregnancy outcomes, and potential confounders among women in the cohort. Women who had vaccine exposure during the prespecified time windows were matched for propensity score in a 1:4 ratio with women who did not have vaccine exposure during the same time windows. Outcomes included spontaneous abortion, stillbirth, major birth defect, small size for gestational age, low birth weight, and preterm birth.
  
  
  
  In matched analyses, exposure to the quadrivalent HPV vaccine was not associated with significantly higher risks than no exposure for major birth defect (65 cases among 1665 exposed pregnancies and 220 cases among 6660 unexposed pregnancies; prevalence odds ratio, 1.19; 95% confidence interval [CI], 0.90 to 1.58), spontaneous abortion (20 cases among 463 exposed pregnancies and 131 cases among 1852 unexposed pregnancies; hazard ratio, 0.71; 95% CI, 0.45 to 1.14), preterm birth (116 cases among 1774 exposed pregnancies and 407 cases among 7096 unexposed pregnancies; prevalence odds ratio, 1.15; 95% CI, 0.93 to 1.42), low birth weight (76 cases among 1768 exposed pregnancies and 277 cases among 7072 unexposed pregnancies; prevalence odds ratio, 1.10; 95% CI, 0.85 to 1.43), small size for gestational age (171 cases among 1768 exposed pregnancies and 783 cases among 7072 unexposed pregnancies; prevalence odds ratio, 0.86; 95% CI, 0.72 to 1.02), or stillbirth (2 cases among 501 exposed pregnancies and 4 cases among 2004 unexposed pregnancies; hazard ratio, 2.43; 95% CI, 0.45 to 13.21).
  
  
  
  Quadrivalent HPV vaccination during pregnancy was not associated with a significantly higher risk of adverse pregnancy outcomes than no such exposure. (Funded by the Novo Nordisk Foundation and the Danish Medical Research Council.).
authors.affiliation: From the Department of Epidemiology Research, Statens Serum Institut, Copenhagen (N.M.S., B.P., D.M.-N., H.S., A.H.); and the Clinical Epidemiology Unit, Department of Medicine, Solna, Karolinska Institutet, Stockholm (B.P.).
authors.forename: Nikolai M
authors.initials: NM
authors.lastname: Scheller
authors.affiliation: From the Department of Epidemiology Research, Statens Serum Institut, Copenhagen (N.M.S., B.P., D.M.-N., H.S., A.H.); and the Clinical Epidemiology Unit, Department of Medicine, Solna, Karolinska Institutet, Stockholm (B.P.).
authors.forename: Björn
authors.initials: B
authors.lastname: Pasternak
authors.affiliation: From the Department of Epidemiology Research, Statens Serum Institut, Copenhagen (N.M.S., B.P., D.M.-N., H.S., A.H.); and the Clinical Epidemiology Unit, Department of Medicine, Solna, Karolinska Institutet, Stockholm (B.P.).
authors.forename: Ditte
authors.initials: D
authors.lastname: Mølgaard-Nielsen
authors.affiliation: From the Department of Epidemiology Research, Statens Serum Institut, Copenhagen (N.M.S., B.P., D.M.-N., H.S., A.H.); and the Clinical Epidemiology Unit, Department of Medicine, Solna, Karolinska Institutet, Stockholm (B.P.).
authors.forename: Henrik
authors.initials: H
authors.lastname: Svanström
authors.affiliation: From the Department of Epidemiology Research, Statens Serum Institut, Copenhagen (N.M.S., B.P., D.M.-N., H.S., A.H.); and the Clinical Epidemiology Unit, Department of Medicine, Solna, Karolinska Institutet, Stockholm (B.P.).
authors.forename: Anders
authors.initials: A
authors.lastname: Hviid
mesh_terms: D000022:Abortion, Spontaneous / Q000453:epidemiology; D000328:Adult; D015331:Cohort Studies; D000013:Congenital Abnormalities / Q000453:epidemiology; D003718:Denmark / Q000453:epidemiology; D005260:Female; D000068857:Human Papillomavirus Recombinant Vaccine Quadrivalent, Types 6, 11, 16, 18 / Q000009:adverse effects*; D006801:Humans; D007230:Infant, Low Birth Weight; D011247:Pregnancy; D011256:Pregnancy Outcome; D047928:Premature Birth / Q000453:epidemiology; D050497:Stillbirth / Q000453:epidemiology; D014611:Vaccination; D055815:Young Adult
chemical_list: D000068857:Human Papillomavirus Recombinant Vaccine Quadrivalent, Types 6, 11, 16, 18