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. Around half of early miscarriages happen because of chromosomal abnormalities in the baby, but in the rest, something else must be going on.

The vaginal microbiome is an environment of micro-organisms – including bacteria and viruses – that live inside the vagina. In order to find out more about the causes of miscarriage, our researchers have been exploring how the vaginal microbiome affects 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 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 the vaginal microbiome.

What’s happening in this project?

Our researchers have been finding out whether it is possible to use a probiotic called Lactin V to increase the amount of Lactobacillus bacteria in the vaginal microbiome. In a small study, the team found Lactin V treatment to be safe, and in most women, the amount of Lactobacillus in the vagina increased. This change persisted even after treatment had stopped. The use of Lactin V in women and birthing people with an imbalance in vaginal bacteria needs exploring further as this treatment may help to prevent miscarriage.

Our researchers have also shown that an unhealthy gut microbiome – the mixture of bacteria in the gut – is linked to miscarriage, while a healthy gut microbiome may reduce the amount of inflammation in the vagina. As a result, the team believe that women and birthing people may be able to reduce their risk of miscarriage by eating a healthy diet that encourages a healthy gut microbiome.

Finally, our researchers want to find a better way of detecting a bacterial imbalance in the vagina. Current tests 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 are now exploring 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 women and birthing people who are most at risk.

What difference will this project make?

This project will help us understand more about why an imbalance in vaginal bacteria can lead to miscarriage and how this can be treated, with the ultimate aim of reducing the number of families experiencing this devastating loss. By developing a quick and easy test to detect an imbalance, we will also make it easier for clinicians to work out which women and birthing people are most at risk and would therefore benefit from treatment.