Do HPV vaccines cause preterm birth?

A new study shows just the opposite! Women who were vaccinated against HPV were less likely to have babies born early than full term.

• A study of nearly 625,000 births linked HPV vaccination before pregnancy to fewer early births.
• Vaccinated women also had lower odds of having babies much smaller than expected.
• The findings suggest possible pregnancy benefits, but do not prove the vaccine caused them.

HPV is a common virus that can cause several types of cancer, including cancer of the cervix—the lower part of the womb.

A new Swedish study published in The BMJ adds evidence that HPV vaccination may also help protect future pregnancies. Researchers studied records from nearly 625,000 first births between 2006 and 2023. More than 92,000 of the mothers had received an HPV vaccine before pregnancy. The vaccine studied protects against four types of HPV.

After accounting for factors such as age and smoking, researchers found that vaccinated women had 5% lower odds of giving birth before 37 weeks, which is considered an early, or preterm, birth. They also had 15% lower odds of giving birth very early, between 28 and 31 weeks, and 8% lower odds of having a baby much smaller than expected for the length of the pregnancy.

These benefits were generally greater among women vaccinated at younger ages.

This matters because babies born too early or very small can face serious health problems. Even a small drop in these problems could help many families. One possible reason is that vaccination prevents HPV infections and reduces the need for treatments that remove damaged tissue from the cervix. Those treatments can raise the risk of early birth.

The vaccine’s protection against cervical cancer is already well supported. An earlier Swedish study of nearly 1.7 million girls and women found an 88% lower risk of cervical cancer among those vaccinated before age 17, compared with those who were not vaccinated. The new study suggests that protection may extend to healthier pregnancies later in life.