Can bacteria affect the risk of miscarriage?

Scientists are looking at the bacteria that live in the vagina to see if certain types of bacteria can affect pregnancy.
  • Author's list

    Dr David MacIntyre, Professor Phillip Bennett, Professor Tom Bourne, Professor Lesley Regan and Raj Rai

    Start date: 2016
    End date: 2022

Why do we need this research?

Too often, doctors are unable to give parents a reason why miscarriage happens. We believe this needs to change.

One area to explore is the role of microorganisms in pregnancy. There are millions and millions of bacteria living on and in our bodies. Usually, these don’t cause any harm – in fact, many are beneficial, like some of the bacteria that live in our guts.

The types of bacteria that live in a woman’s vagina, womb and gut naturally change during pregnancy. By looking at these bacteria, our scientists think that they might be able to shed light on why some miscarriages happen.

What’s happening in this project?

To find out how different types of bacteria can affect pregnancy, researchers funded by Tommy’s carried out a study that included women who were attending a general gynaecology clinic, as well as those experiencing bleeding, pain or miscarriage and those who had suffered recurrent miscarriage. The women in the study donated samples of their placenta and the lining of the womb, as well as swabs from the vagina to collect the bacteria living there; samples were available from 93 women who miscarried and 74 women whose pregnancies went to term.

Our scientists looked at vaginal swabs from the women taking part in the study and found that lower amounts of a type of bacteria called Lactobacillus were connected to increased inflammation in the vagina that may have increased the risk of miscarriage. Interestingly, some of the women whose pregnancies went to term also had low levels of Lactobacillus, but these women did not have as much inflammation, which probably explains why their pregnancies were successful. The team are continuing to look at this to try and understand it more.

What difference will this project make?

By finding out how the mixture of bacteria in the vagina might affect pregnancy, our researchers hope their work will allow more women to get an answer to the question of why their miscarriage happened. It may also be possible to develop treatments that can be used either before pregnancy or during the first trimester that boost the levels of Lactobacillus in the vagina and help to reduce the chances of miscarriage.

Thanks for your interest in our research

Tommy's funds research across the UK investigating the reasons for miscarriage, stillbirth and premature birth. We can keep you updated on ways you can support our work. If you would like to join our fight against baby loss and premature birth, click here.