HPV Vaccination: Can It Lower Preterm Birth Risk?

What did the HPV vaccination and pregnancy study find?

Researchers used Swedish national registers covering 2006–2023 to conduct a matched case-control study within a population of 624,713 singleton births to first-time mothers aged 16–35. Of these women, 92,620 had received the quadrivalent HPV vaccine before pregnancy. This formulation targets four HPV types. [BMJ study](https://pubmed.ncbi.nlm.nih.gov/42843853/)

After adjustment for potential confounding factors, the odds ratio for birth before 37 weeks was 0.95, with a 95% confidence interval of 0.91–0.99. That represents approximately 5% lower odds, rather than a five-percentage-point reduction in the probability of premature delivery. The distinction matters: an odds ratio alone does not tell an individual how much their absolute chance of an early birth might change. [BMJ study](https://pubmed.ncbi.nlm.nih.gov/42843853/)

How might HPV vaccination affect pregnancy outcomes?

HPV infection and treatment for abnormal cervical cells have both been associated with pregnancy complications. Preventing infection could therefore offer benefits that extend into later pregnancies. The researchers also found stronger associations among women vaccinated before age 17, a pattern consistent with the advantages of vaccination before HPV exposure. However, this remains a possible explanation rather than proof of how vaccination affected these births. [Karolinska Institutet](https://news.ki.se/hpv-vaccinated-women-had-a-lower-risk-of-preterm-birth)

Vaccinated and unvaccinated groups can differ in ways that statistical adjustment does not fully capture. Health behaviors and healthcare use, for example, could influence both vaccination and pregnancy outcomes. Because vaccination was not randomly assigned, the study cannot eliminate these alternative explanations. Its size makes the association informative, but does not remove uncertainty about causation. The authors' institution explicitly identifies this limitation. [Karolinska Institutet](https://news.ki.se/hpv-vaccinated-women-had-a-lower-risk-of-preterm-birth)

Should people planning pregnancy get the HPV vaccine?

The established reason for HPV vaccination remains prevention of new infections and HPV-related cancers. In the United States, CDC recommends catch-up vaccination through age 26 for people not adequately vaccinated earlier; some adults aged 27–45 may benefit after discussing their circumstances with a clinician. Eligibility and schedules vary internationally. This study does not establish HPV vaccination as a treatment specifically prescribed to prevent preterm birth. [CDC recommendations](https://www.cdc.gov/hpv/hcp/vaccination-considerations/)

CDC does not recommend HPV vaccination during pregnancy. If pregnancy is discovered after a dose, remaining doses should be delayed until pregnancy is complete; no intervention is needed solely because vaccination occurred inadvertently. Routine pregnancy testing before vaccination is unnecessary. These recommendations distinguish an accidental exposure from deliberately scheduling vaccination during pregnancy. [CDC pregnancy guidance](https://www.cdc.gov/vaccines-pregnancy/hcp/vaccination-guidelines/index.html)

Vaccination also does not replace cervical screening or treat an existing HPV infection. Its protective antibodies help prevent future infection with targeted HPV types, while screening identifies changes that may require follow-up. People who have been vaccinated should continue screening according to the recommendations applicable to their age and medical history. [National Cancer Institute](https://www.cancer.gov/about-cancer/causes-prevention/risk/infectious-agents/hpv-vaccine-fact-sheet)