Changed maternal vaginal microbiota (bacteria) may negatively impact women’s newborns, finds a new study published in Endocrinology.

Researchers cite the vaginal microbiome is “the primary source for normal gut colonization, host immune maturation, and metabolism,” and any changes in microbiota are transferrable during birth. This is why the source is considered a “critical window of neurodevelopment.” So what could trigger such a change? Maternal stress.

“Mom's stress during pregnancy can impact her offspring's development, including the brain, through changes in the vaginal microbiome that are passed on during vaginal birth,” Dr. Tracy Bale, study author of the University of Pennsylvania, said in a press release. “As the neonate's gut is initially populated by the maternal vaginal microbiome, changes produced by maternal stress can alter this initial microbe population, as well as determine many aspects of the host's immune system that are also established during this early period.”

Bale and her team used their established mouse model of maternal stress, which identifies predator odor, restraint, and novel noise as stressors. Two days after mice gave birth, researchers collected tissue from the vaginal lavages and maternal fecal pellets; offspring gut was analyzed, too. The results showed pregnancy disrupted vaginal microbiota, with disrupted bacteria then disrupting offspring gut microbiota composition.

In 2014, a similar study concluded pregnant women’s stress could cause damage to children. But the ways in which these studies were conducted are totally different. The previous study, for one, used artificial means to look at stress by simply pumping pregnant mice full of hormones called glucocorticoids, Bale explained in an email to Medical Daily. This is but one aspect of stress.

What’s more is the present study developed their model of maternal stress “in very early pregnancy over a decade ago and have been using this model to look at the mechanisms by which mom’s stress in early pregnancy contributes to changes in the offspring brain,” Bale said. Over the years, the model has been used to study placenta and the role it may play in development.

“In the most recent study, we have now examined the maternal vaginal microbiome, how stress changes the microbial content, and how this is passed directly on to the offspring at birth and changes their gut bacterial content,” Bale said. “These findings were also sex-specific, where the male and female offspring from the same mom showed differences in how mom’s stress affected these measures.”

The translational potential of findings like these could inspire new procedures to ensure offspring are exposed to healthy microbiota.

Source: Bale TL, et al. Alterations in the vaginal microbiome by maternal stress are associated with metabolic reprogramming of the offspring gut and brain, Endocrinology. 2015.