HPV Infection During Pregnancy Ups Risk for Premature Birth

Jaleesa Baulkman

September 20, 2021

Persistent human papillomavirus (HPV) 16 and HPV 18 during a pregnancy may be associated with an increased risk of premature birth.

Findings published online in JAMA Network Open found that 15.9% of individuals who had a persistent HPV 16 or 18 infection during the first and third trimesters of their pregnancy gave birth prematurely, compared with 5.6% of those who did not have an HPV infection at all.

The findings prompted the question of "the pathophysiology of HPV in pregnancy and how the virus is affecting the placenta," said Lisette Davidson Tanner, MD, MPH, FACOG, who was not involved in the study.

Researchers said the findings are the first to show the association between preterm birth and HPV, which is an incurable virus that most sexually active individuals will get at some point in their lives, according to the Centers for Disease Control and Prevention.

"The results of this study are very important in helping us understand the burden caused by HPV in pregnancy," study author Helen Trottier, MSc, PhD, researcher at the Centre Hospitalier Universitaire Sainte-Justine, said in an interview. "We may have just pinpointed an important cause of preterm birth that has so far been unexplained."

Trottier and colleagues examined data from 1,052 pregnant women from three university-affiliated health care centers in Montreal between Nov. 8, 2010, and Oct. 16, 2016.

Only 5.6% of those who did not have an HPV infection had a premature birth, compared with 6.9% of those who tested positive for any HPV infection in the first trimester.

When looking at the first trimester, researchers found 12% of those diagnosed with HPV 16 and 18 had a preterm birth, compared to 4.9% of those who had a high-risk HPV infection other than HPV 16/18. When looking at the third trimester, researchers found that 15.9% of those with HPV 16/18 had an increased risk of giving birth prematurely, compared to those who had other high-risk HPV infections.

When researchers looked at the persistence of these HPV infections, they found that most HPV infections detected in the first trimester persist to the third trimester. The findings also revealed that persistent vaginal HPV 16/18 detection was significantly associated with all preterm births and spontaneous preterm births. This association was also found among those who had HPV infections detected in their placentas.

Meanwhile, 5.8% of those who had an HPV infection only during the first trimester experienced a preterm birth.

The researchers also found that HPV infections were frequent in pregnancy even among populations "considered to be at low risk based on sociodemographic and sexual history characteristics," they wrote. Trottier said she hopes the findings will strengthen support for HPV vaccination.

Trottier's study adds to a growing body of research regarding the adverse effects of HPV, according to Tanner, assistant professor of gynecology and obstetrics at Emory University, Atlanta. "It is already well known that HPV is associated with a number of anogenital and oropharyngeal cancers," Tanner said in an interview. "The potential association with preterm birth only adds weight to the recommendations to screen for and prevent HPV infection."

HPV 16 and 18 are high-risk types that cause about 70% of cervical cancers and precancerous cervical lesions, according to the World Health Organization. However, there are three HPV vaccines – 9-valent HPV vaccine (Gardasil), quadrivalent HPV vaccine (Gardasil®, 4vHPV), and bivalent HPV vaccine (Cervarix) – that help protect against HPV 16/18.

The findings strengthen the benefits of HPV vaccination, Trottier explained. "There is no cure when the HPV infection is present," Trottier said. "If the link [between preterm birth and HPV infections] is indeed causal, we can expect a greater risk of preterm delivery in these women. The effective tool we have is the HPV vaccination, but it should ideally be received before the start of sexual activity in order to prevent future infections that could occur in women."

The American College of Obstetricians and Gynecologists recommends HPV vaccination for girls and women between the ages of 11 and 26 years old. However, Tanner said, women aged 27-45 who were previously unvaccinated may still receive benefit from the vaccine.

"Despite the known efficacy of the vaccine, only 50% of patients are up to date with their HPV vaccination," Tanner explained. "This study further highlights the need to educate and encourage patients to be vaccinated."

The researchers said future studies should investigate the association of HPV vaccination and vaccination programs with the risk of preterm birth.

The experts disclosed no conflicts of interest.

This article originally appeared on MDedge.com, part of the Medscape Professional Network.

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