Mothers-to-be infected with human papillomavirus (HPV) are nearly four times more likely to have a premature baby, a study has suggested.
Canadian academics found a 'significant' link between pregnant women giving birth early and HPV types 16 and 18, which cause 70 per cent of cervical cancers.
Eight out of 10 people will be infected at some point in their life with HPV, which is usually spread through sex.
Experts at the University of Montreal have yet to pinpoint any reason as to why being infected may drive up the risk of premature birth.
But they suggested the virus may cause changes in the vaginal microbiome, which could trigger inflammation and lead to an early delivery.
Genital tract viruses - the most common of which is HPV - could also leave women more susceptible to bacterial infections which can trigger pre-term labour, medics said.
If a causal link is confirmed, then a HPV vaccine may reduce preterm birth rates and the 'associated burden' on health services, the scientists said.
Preterm birth is one of the leading causes of death among newborns and can cause lifelong health problems.
In the UK, one in every 13 babies is born premature – classified as before week 37 of pregnancy – while the figure for the US is one in 10.
A total of 60,000 babies are born prematurely in the UK every year, equating to around eight in every 100 births (file)
Eight out of 10 people will be infected at some point in their life with HPV, which is usually spread through sex
The cause is a mystery for the majority of premature births, but smoking as well as conditions such as diabetes have been linked to early labour.
Long-term effects for children born preterm include disabilities related to learning, seeing and hearing.
