A common bacteria about a third of women carry has been linked to premature delivery and stillbirths in a study using mice.
Group B Streptococcus (GBS) bacteria can be found in the vagina of 20 to 30 per cent of all women and is regularly tested for in late pregnancy.
It's known the bacteria can cause a baby to develop a serious infection, like meningitis or pneumonia, if a woman who carries the bug is not treated with anitbiotics - usually penicillin.
There is about a 1 in 200 chance of that happening, according to infectious diseases expert Professor Sanjaya Senanayake from the Australian National University (ANU).
There has been, however, some conjecture whether GBS could cause problems before delivery, such as stillbirths and premature delivery.
But a study conducted by researchers at the Indian Institute of Technology - Bombay, published in the journal PLOS Pathogens, has found a link.
When doctors look at a placenta under a microscope after a stillbirth they will see inflammation but they won't always find the cause, says Prof Senanayake.
"What these scientists are saying is that they found the bug, that can cause problems in newborns, can produce these little packets of inflammation and without moving from the vagina can send these packets of inflammation into the womb and can cause induced premature labour and stillbirths," Prof Senanayake said.
He said that would explain why in some cases of stillbirths and premature babies inflammation could be seen under the microscope but the bacteria could not.
According to the study, 60 per cent of fetuses were born prematurely - by day 18 of pregnancy - after the scientists directly injected the amniotic sac in the pregnant mice with the bacteria.
An increased frequency of fetal death in utero was also observed.
Prof Senanayake says the finding could potentially have implications for the management of GBS during pregnancy.
"Does that mean then we start doing swabs earlier in pregnancy to see if it's there?
"And if it is there maybe giving antibiotics to try and get rid of it," said Prof Senanayake.
However, it was too early to suggest a definitive link had been found despite mice being gentically similar to humans, he warned.
