TW: Miscarriage
Vaginal bacteria and the risk of miscarriage in early pregnancy.
Sadly, early miscarriages are all too common. In the first 3 months, 1 in 4 women will have a miscarriage. And quite distressingly, under the NHS women will only be tested to find out why after they have suffered through 3 in a row (1). 1 in 100 women will experience recurrent miscarriages.
Half of the miscarriages that occur in the first 3 months of pregnancy are due to chromosomal abnormalities in the baby, which occur by chance (2). Chromosomes are blocks of DNA that contain instructions for the baby’s development.
After 3 months, the risk of having a miscarriage does reduce significantly.
New findings from the London team at Tommy’s National Centre for Miscarriage Research suggest that early miscarriage may be linked to the balance of bacteria in the vagina (3). In a study the team published in January 2022 they found that:
Out of 167 women, 93 pregnancies ended in miscarriage and 74 went to full term
In the miscarriage group, chromosomal abnormalities were ruled out
In the women with no chromosomal abnormalities, it was found that their vaginal microbiome was low in Lactobacillus.
The lower amounts of Lactobacillus in the vagina were linked 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.
The first author of the study, Dr Karen Grewal, from Imperial’s Department of Metabolism, Digestion and Reproduction, said: “Our findings may present a fresh perspective on the causes of miscarriage. There are multiple ideas for how this inflammation could lead to pregnancy loss, such as certain vaginal bacterial organisms triggering upstream inflammation that causes a breakdown within the lining of the womb” (4).
However, these underlying mechanisms are still poorly understood.
The same researchers are now carrying out a project to better understand how an imbalance in vaginal bacteria leads to miscarriage, what testing can be implemented for early diagnosis and what therapeutic treatments will work as an intervention, this research is ongoing until 2024.
They will be exploring several proposed mechanisms of action, 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.
The team are using Desorption Electrospray Ionisation Mass Spectrometry (DESI-MS) to explore whether this method can be used to detect a bacterial imbalance in the first trimester of pregnancy. And the researchers will be looking to see if it’s possible to use probiotic treatments to increase the amount of Lactobacillus bacteria in the vagina and prevent miscarriage.
It’s very early days and more research is needed but the great work that Tommy’s is carrying out could lead to quick and easy testing to detect an imbalance and hopefully show that probiotic treatment can help the women impacted so that this staggering number of early miscarriages in the UK decreases.
Exciting times are ahead in this area of research with more to come.
If you would like further support regarding miscarriages, you can find out more on Tommy’s website.
References:
How common is miscarriage? (n.d.). Together, for every baby - Charity for Babies | Tommy's. https://www.tommys.org/pregnancy-information/im-pregnant/early-pregnancy/how-common-miscarriage
Suzumori N. and Sugiura-Ogasawara M., Genetic Factors as a Cause of Miscarriage, Current Medicinal Chemistry 2010; 17(29). https://dx.doi.org/10.2174/092986710793176302
Vaginal bacteria and the risk of miscarriage. (n.d.). Together, for every baby - Charity for Babies | Tommy's. https://www.tommys.org/our-research/our-research-projects/miscarriage-research/vaginal-bacteria-and-risk-miscarriage
Grewal, K., Lee, Y. S., Smith, A., Brosens, J. J., Bourne, T., Al-Memar, M., Kundu, S., MacIntyre, D. A., & Bennett, P. R. (2022). Chromosomally normal miscarriage is associated with vaginal dysbiosis and local inflammation. BMC Medicine, 20(1). https://doi.org/10.1186/s12916-021-02227-7
