A study conducted on mice shows that an unhealthy vaginal microbiome in future mothers would increase the risk of mortality, as well as impaired development of the baby. However, it is possible to counteract these harmful effects with a balanced diet.
- In France, it is estimated that around 80% of babies are born vaginally and 20% by caesarean section.
- When born by C-section, babies do not benefit from the same healthy bacteria to build their vaginal microbiome as those born vaginally.
- This vaginal microbiome can however be altered if the mother suffers from a chronic disease (diabetes, hypertension, etc.) or in the event of a diet low in fibre.
When they come into the world vaginally, babies pass through their vagina before being confronted with the air that surrounds them. They then collect the bacteria from the vagina and the perineum area which will colonize his body and his digestive system to constitute his first microbiota. These bacteria are essential because they participate in the proper development of the immune system.
However, some women with chronic diseases such as diabetes or hypertension, but also those living in poor neighborhoods where access to care and nutrition is limited, are at greater risk of having an unhealthy vaginal microbiome, which which increases the likelihood of infections. “We know that what is healthy for the mother is also healthy for the baby’s brain development and that stress also contributes to the risk of disease”explains Tracy Bale, professor of pharmacology and lead author of a study published in NatureCommunications.
Accompanied by her fellow researchers from the University of Maryland School of Medicine, Tracy Bale shows that an unhealthy vaginal microbiome in pregnant mothers, combined with an unhealthy diet, contributed to increased pup mortality and impaired development of surviving babies.
A higher mortality risk
To find out if an unhealthy vaginal microbiome could affect the baby’s development, the researcher and her team used mouse pups tested samples of the vaginal microbiome of pregnant women from baby mice born by cesarean section. They first applied the healthy or unhealthy bacterial samples to the vagina of mice to recreate the gestational environment. Then, the pups born by caesarean section ingested the same vaginal microbiomes, mimicking vaginal birth exposure.
The researchers studied turned on and off genes in the cubs’ brains to see how the mothers’ vaginal microbes affected the development of their young. They found that the immune system of these little ones was activated and developed very early.
To model vulnerable populations, the researchers then repeated the study, but added the risk factor for prediabetes and obesity by replacing the pregnant mice’s healthy food with an unhealthy, high-fat, low-fiber diet. . 60% of baby mice exposed to unhealthy human microbiomes and fed the unhealthy diet died within 48 hours of birth. In contrast, with the same microbiome exposure, but with a healthy high-fiber diet, the mortality rate fell by more than half.
The key role of a good diet
Dr. Bale explains these results because soluble fibres, such as those found in fruits and vegetables, ferment in the intestine, allowing bacteria to produce short-chain fatty acids, which are necessary for baby’s brain development and which are also effective anti-inflammatory agents for the mother.
“The component of the vaginal microbiome has led to dramatic changes in the brain through the development of the fetal immune system, and it appears that this overactive immune system increases the risk of infant mortality”explains the researcher, who hopes that this work will improve the health of mothers and their children by reducing infant mortality rates, particularly among the most vulnerable populations.
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