HPV vaccination before pregnancy linked to lower odds of preterm birth

Clinical takeaway: Prioritize timely HPV vaccination and review vaccination status during preconception care. These findings suggest a possible additional reproductive benefit, particularly with earlier vaccination. HPV vaccine remains deferred during pregnancy.

HPV infection and procedures that remove cervical precancerous tissue have been linked to preterm birth. Preventing infection could therefore offer benefits that extend beyond cancer prevention.

A nationwide Swedish study adds evidence for that possibility, linking quadrivalent HPV vaccination before pregnancy to modestly lower odds of several adverse birth outcomes.

Researchers analyzed 624,713 singleton first births among women aged 16–35 years between 2006 and 2023. About 15% had received at least one vaccine dose before conception. For each outcome, affected women were matched with controls by maternal age and year of conception, with additional adjustment for smoking, BMI, socioeconomic factors, and medical conditions.

Compared with no vaccination, prior vaccination was associated with 5% lower adjusted odds of preterm birth before 37 weeks. Associations were stronger for very preterm birth at 28–31 weeks, with 15% lower odds. Severe small-for-gestational-age birth—birth weight below the third percentile—was associated with 8% lower odds.

Timing mattered. Women vaccinated before age 17 had 10% lower adjusted odds of preterm birth and 11% lower odds of spontaneous preterm birth. Vaccination at age 17 or older was not significantly associated with either outcome.

Preventing HPV infection and reducing the need for cervical procedures are possible explanations, although the study could not establish the mechanism or prove causation.

“Risk reduction was generally greater among women vaccinated at earlier ages,” the study authors concluded.

Source: Zhang Z, et al. (2026 Oct 7) BMJ. Quadrivalent human papillomavirus vaccination before pregnancy and pregnancy outcomes: nationwide, population based case-control study