HPV infection may increase risk of preterm birth

Treatment for abnormal cervical cell changes due to human papillomavirus (HPV) infection was previously known to increase pregnant women’s risk of preterm birth — defined as birth before 37 weeks’ gestation. Now, researchers from the University of Gothenburg say a connection can be seen between the virus itself and the risk for preterm birth, according to a study published in the journal PLOS Medicine.

The team’s study is based on birth particulars registered in the Swedish Medical Birth Register, which have been merged with the country’s National Quality Registry for Cervical Cancer Prevention and the Swedish Cancer Register. Altogether, 1,044,023 births between 1999 and 2016 were included. Of the women concerned, 23,185 had previously received treatment, while 11,727 were untreated and had a positive HPV screening test immediately before or during their pregnancy.

Of the women previously treated for cervical intraepithelial neoplasia (CIN), 9.1% gave birth prematurely. The corresponding proportion in the group with HPV infection in conjunction with their pregnancies was 5.9%. This was a statistically significant increase compared with a reference group of women whose cervical screening test had always been normal, of whom 4.6% gave birth prematurely.

Verena Sengpiel, Associate Professor of Obstetrics and Gynecology at Gothenburg’s Sahlgrenska Academy and obstetrician at Sahlgrenska University Hospital, is the study’s last author. She noted, “Our study is register based and, although we’ve adjusted for various factors in the analyses, we can’t reliably answer the question of whether it’s the virus itself that causes the pregnancy and childbirth complications. All we can do is show a statistical association.

“Soon we’ll be able to see how the incidence of preterm birth is affected after the vaccination program against HPV has been introduced. That will give us more information about whether there’s a causal connection between HPV infection itself and delivery outcome.”

Johanna Wiik, a PhD student in obstetrics and gynaecology at Sahlgrenska Academy and also a gynaecologist and obstetrician at Sahlgrenska University Hospital, is the first author of the study. She noted that “the increase in risk for preterm birth is small for the individual woman carrying HPV”, but said the results “support that young people should get into the vaccination program against HPV”. The researchers also emphasised the importance of heeding calls for gynaecological cell sampling, in order to detect any cervical cell changes due to HPV infection.

“The earlier these abnormal cell changes are detected, the better we can follow and treat them,” Wiik said. “And when you’re admitted to maternity care, it’s a good idea to tell your midwife if you’ve had cervical cell changes, and whether you’ve been treated for them. Then the maternity health staff can take that information into account when planning the monitoring of your pregnancy.”

Image credit: ©stock.adobe.com/au/ruigsantos

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