Poor diet in pregnancy can lead to an unhealthy vaginal microbiome, greater risk of infant death 

Pregnant mothers following an unhealthy diet may have an unhealthy vaginal microbiome, which is linked to a greater risk of infant death and changes to their development. Changing the mother’s diet to a healthier plan, however, decreased a baby’s mortality risk, according to recent research.

Babies delivered vaginally are exposed to the mother’s vaginal microbiome, where their skin is coated and they ingest some of their first microbes outside the sterile womb. Since a baby’s immune system is underdeveloped at birth, exposure to their mother’s microbes helps to protect them by exposing them to beneficial bacteria. 

Previous work from the team had shown the importance of vaginal microbial exposure to newborn infants with mouse pups born through C-section from stressed mothers had neurodevelopmental changes in how they respond to stress compared to pups born from the vaginal microbiome.

Importance of vaginal microbiome in pregnancy

Unlike the gut microbiome, where diversity in bacterial species is celebrated, the vaginal microbiome is dominated by a bacterial called Lactobacillus, which is involved in creating antimicrobial compounds. Having a diversity of microbes in the vaginal microbiome makes it unhealthy. Other research on the vaginal microbiome showed that human vaginal microbiomes fall into five groups based on the dominant microbe, having four healthy variations and one ‘unhealthy’ variation.

Women with chronic diseases such as diabetes or high blood pressure, and women living in impoverished neighborhoods with little access to healthcare and good nutrition are at a higher risk of having an unhealthy gut microbiome. However, the researchers suggest having access to diets rich in high-fiber fruits and vegetables may offset many of the harmful effects of an unhealthy vaginal microbiome.

“We know what is healthy for mom is healthy for baby’s brain development, and on the flip side stress contributes to disease risk” Tracy Bale, PhD, Professor of Pharmacology at the University of Maryland School of Medicine and Director of the Center for Epigenetic Research in Child Health & Brain Development and study author said in a press release. “We wanted to identify biological factors that predict these negative health outcomes and determine how each one contributes to these inequities in our society.”

Mouse study reveals new insights

The research team used vaginal microbiome samples from pregnant women and applied them to the healthy or unhealthy bacterial samples in a mouse’s vagina to replicate a gestational environment. Mouse pups delivered via C-section were given the vaginal microbiome samples, mimicking vaginal birth exposure.

Results showed that C-section delivered babies exposed to vaginal microbiome samples had early activation and development of their immune system than babies unexposed to it.

The researchers next looked at how limited access to medical care and healthy diets affected infant development. They replicated the study but with the addition of swapping the food for pregnant mice with a high-fat, low-fiber diet. Mothers with an unhealthy diet, and in turn, an unhealthy microbiome, had 60% of mouse pups die within 2 days of delivery. However, exposure to a microbiome on a high-fiber diet cut the mortality risk by more than half.

The study was published in the journal Nature Communications.

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