Peri-Conception Human Papillomavirus Vaccination Exposure and Risk of Birth Defects: A Population-Based Retrospective...

Women of childbearing age may receive human papillomavirus (HPV) vaccination during pregnancy, yet evidence on birth defects (BDs) risks remains limited. This study evaluates associations between peri-conception (from 30 days before the last menstrual period and the end of the first trimester) HPV vaccination and BDs.

This population-based retrospective cohort study included pregnancies with last menstrual periods between March 2018 and March 2021 in Xiamen, China. Propensity score matching (PSM) based Poisson regression with robust variance estimation was used to estimate the adjusted relative risk (aRR) of exposure for total BDs and 10 organ system-specific BDs. Subgroup analysis (Different vaccine valences) and eight sensitivity analyses were performed.

A total of 177,574 pregnancies were included, of which 300 were exposed to the HPV vaccine during the peri-conception period. The rate of peri-conception vaccine exposure increased from 0.07% in 2018 to 0.34% in 2021. After 1:4 PSM, peri-conception HPV vaccination was not associated with an increased risk of total BDs (aRR 0.66, 95% confidence interval [CI] 0.26-1.70). Similarly, no significant association was found between HPV vaccination and the organ system-specific BDs. Subgroup analysis showed exposure to the 4vHPV (aRR 0.99, 95% CI 0.34-2.94) and 9vHPV (aRR 0.98, 95% CI 0.11-8.69) vaccines were also not associated with a higher risk of total BDs. All sensitivity analyses, including negative control, demonstrated the robustness of the results.

This study suggests that exposure to the HPV vaccine during the peri-conception period does not increase the risk of BDs. However, the precision of organ system-specific BDs remains limited, necessitating validation through larger-scale studies.

This study was registered at ClinicalTrials.gov (NCT06180447).