The quadrivalent human papillomavirus (HPV) vaccine was not associated with any adverse pregnancy outcomes when inadvertently given during pregnancy, according to the findings from a nationwide Danish study.
“Our results are consistent with other evidence that does not indicate that the vaccination of pregnant women with inactivated virus, bacterial, or toxoid vaccines generally confers a higher risk of adverse pregnancy outcomes than no such vaccination. Our results also confirm and considerably expand on results from previous studies of the quadrivalent HPV vaccine,” wrote Nikolai M. Scheller, MD, of the Statens Serum Institut, Copenhagen, and his colleagues.
Quadrivalent HPV vaccination was not associated with any increase in risk for major birth defects (prevalence odds ratio, 1.19), spontaneous abortion (hazard ratio, 0.71), preterm birth (prevalence OR, 1.15), small size for gestational age (prevalence OR, 0.86), or low birth weight (prevalence OR, 1.10). It also was not associated with increased risk for stillbirth, but this outcome occurred in only two case patients and four controls, making it “impossible to draw clinically meaningful conclusions” regarding the risk for stillbirth, Dr. Scheller and his colleagues reported (N Engl J Med. 2017;376:1223-33).
“Because many [adverse] pregnancy outcomes are rare, our study did not have the statistical power to assess the risks of stillbirth and specific major birth defects associated with quadrivalent HPV vaccination. Larger studies would be needed to address these outcomes,” they added.
Novo Nordisk and the Danish Medical Research Council funded the study. Dr. Scheller reported having no relevant financial disclosures; two of his coauthors reported receiving research grants from the Novo Nordisk Foundation and the Danish Medical Research Council.