Vaginal bacteria and the risk of miscarriage

Our researchers have already shown that low levels of a bacteria called Lactobacillus in the vagina are linked to miscarriage. Now, they are trying to find ways to easily detect and treat this bacterial imbalance in order to reduce the risk of miscarriage.
  • Authors list

    Dr David MacIntyre, Professor Phillip Bennett, Professor Tom Bourne, Professor Lesley Regan, Raj Rai, Professor Siobhan Quenby, Professor Jan Brosens, Professor Arri Coomarasamy

    Start date: 2021
    End date: 2024

Why do we need this research?

1 in 4 pregnancies end in loss and many parents never find out why. We believe this needs to change.

To find out more about the causes of miscarriage, our researchers looked at the effects of bacteria on pregnancy. They showed that lower amounts of a type of bacteria called Lactobacillus in the vagina were connected to increased inflammation and a higher risk of miscarriage. They found that some women with low levels of Lactobacillus did have healthy pregnancies, but that these women did not have as much inflammation in the vagina.

Our researchers now want to understand how an imbalance in vaginal bacteria leads to miscarriage and whether this can be treated. They also want to find a better way of diagnosing problems with vaginal bacteria.

What’s happening in this project?

By carrying out studies in the lab, our researchers hope to work out why low amounts of Lactobacillus bacteria in the vagina can cause miscarriage. There are several proposed mechanisms that will be explored, including the possibility that miscarriage occurs because of inflammation, or that bacteria from the vagina reach the womb and affect implantation and the formation of the placenta.

As well as these studies, our researchers want to find a better way of detecting whether a woman has a bacterial imbalance in her vagina. At the moment, the tests that are used are too slow and expensive, while other tests do not give enough detail to be useful. In collaboration with other researchers, our team have developed a new way of looking at the bacteria present in the vagina by using something called Desorption Electrospray Ionisation Mass Spectrometry (DESI-MS). Our team will now explore whether the DESI-MS method can be used to detect bacterial imbalance in the first trimester of pregnancy, and hope that in the future it can be used routinely to identify those women who are more likely to miscarry.

Finally, our researchers want to see if it is possible to use probiotic treatments to increase the amount of Lactobacillus bacteria in the vagina and prevent miscarriage. The team are planning two clinical trials of a probiotic called Lactin V – one in women with recurrent miscarriage (defined as three or more miscarriages in a row) and one in women who have had one previous miscarriage.

What difference will this project make?

This project will help us understand more about why an imbalance in vaginal bacteria can lead to miscarriage. Also, the development of a quick and easy test to detect an imbalance will make it much easier for clinicians to work out which women are most at risk and would therefore benefit from treatment. We hope that our clinical trials will show that probiotic treatment can help these women, ultimately leading to a reduction in the number of families having to endure a devastating miscarriage.