A study led by the University of Cambridge has found that the presence of Bifidobacterium breve, a common probiotic bacteria, in the gut of pregnant females can improve placenta function and may reduce pregnancy complications such as preeclampsia and miscarriage.
The research, published in the Journal of Translational Medicine, provides evidence that Bifidobacterium breve regulates the production of hormones in the placenta that are vital for a healthy pregnancy. The study involved mice, comparing those with no gut bacteria to those with Bifidobacterium breve during pregnancy. Mice without this bacteria experienced more complications, including fetal growth restriction, low blood sugar in fetuses, and increased fetal loss.
According to Dr Jorge Lopez Tello, first author of the report who conducted the work at the University of Cambridge’s Department of Physiology, Development and Neuroscience: “Our results open up an entirely new way to assess the health of a pregnant mother and her developing fetus by looking at the mother’s gut microbiome.” He added: “Everybody ignores the placenta - after nine months of pregnancy it just gets thrown in the bin. But now we understand more about how it works, in the future pregnancy complications like gestational diabetes, preeclampsia, miscarriage and stillbirth might be prevented simply by adjusting the mother’s gut microbes to improve the function of the placenta.”
The study revealed over 150 biological processes involving more than 400 proteins were different in placentas from mice with Bifidobacterium breve compared to those without. Mice with this bacterium had better nutrient absorption through their placentas and higher production of key hormones such as prolactins and pregnancy-specific glycoproteins.
Researchers highlight that using mice allowed them to control factors like diet and activity, ensuring findings could be attributed specifically to Bifidobacterium breve. While these results are promising for human pregnancies as well, further research is needed to understand how these bacteria interact within humans' complex gut microbiomes and whether they can be safely adjusted with probiotics.
Bifidobacterium breve occurs naturally but its levels may change due to stress or obesity during pregnancy. It is available as a supplement in many probiotic drinks and tablets.
Professor Amanda Sferruzzi-Perri from Cambridge's Department of Physiology, Development and Neuroscience said: “Our research reveals a whole new layer of information about how pregnancy works, and will help us find new interventions that can improve the chances of a healthy pregnancy for mother and baby.”
Professor Lindsay Hall from University of Birmingham’s College of Medicine and Health commented: “It’s exciting to think that beneficial microbes like Bifidobacterium - which naturally support gut and immune health - could be harnessed during pregnancy to improve outcomes. Using something like a probiotic offers a promising alternative to traditional therapeutics, potentially reducing risks while enhancing wellbeing in mother and baby.”
The study was funded mainly by Wellcome.
Reference: Lopez-Tello, J. et al: ‘Placental endocrine function is controlled by maternal gut Bifidobacterium in germ-free mice.’ Journal of Translational Medicine, October 2025. DOI: 10.1186/s12967-025-07198-4