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  • Stress in pregnant mice appeared to alter the bacterial flora of their gut as well as placentas.
  • Similar changes in bacterial flora were replicated in the intestinal tract of the female offspring as well, that persisted into adulthood.
  • The placenta and brain of the female offspring showed increased inflammatory markers and altered growth factors.
  • Mice exposed to prenatal stress showed anxiety and had cognitive and learning difficulties in spite of never being stressed after birth.
  • Maternal stress induced changes in gut microbiome may affect the mental health of the offspring, according to researchers at The Ohio State University.

Aim of the Study

Earlier research has found associations between maternal stress in animals as well as humans to behavioral problems in their children and negatively impacting their mental health . This study attempts to explain how and why.
Stress-Related Changes in Maternal Microbiome May Have Lasting Effect in Children

"We already understand that prenatal stress can be bad for offspring, but the mystery is how," said Gur, a psychiatrist who is a member of Ohio State Wexner Medical Center's Institute for Behavioral Medicine Research.

Details of the Study

To induce stress in pregnant mice, they were subjected to two hours of restraint for a week. For comparison, the authors left undisturbed another set of mice.

The gut bacteria of both groups of mice were studied after obtaining fecal samples.

Findings of the Study

  • Pregnant mice exposed to stress showed alterations in the bacterial flora of their guts and placentas.
  • The intestinal tracts of their female offspring were also similarly affected, and these changes persisted into adulthood.
  • Inflammatory markers were increased and growth factors showed alterations in the fetal placenta, as well as the fetal and adult brain of the offspring.
  • Levels of a supportive protein termed brain-derived neurotrophic factor (BDNF) were found to be decreased.
  • Female offspring of stressed mothers performed poorly in cognitive tests, and suffered from anxiety. "These mice were more anxious, they spent more time in dark, closed spaces and they had a harder time learning cognitive tasks even though they were never stressed after birth," said Dr Gur.
  • The researchers also found interesting changes in the male offspring but say that part of the study is still in the nascent stages

What the Findings Imply

Maternal gut and reproductive tract bacteria are the first to colonize in the fetus and newborns. Thus, it is hypothesized that altered maternal microbiome may be a starting point for affecting the mental health of the offspring later in life.

Alterations in inflammatory markers and growth factors in the placenta and fetal brain suggest that the microbes may be affecting important dynamics even before birth.

Future Plans of Research

Interesting effects of maternal stress on male offspring have been noted, but is being planned for a future study.

The authors wish to research more on the links between gut bacteria and the brain in future studies. They plan to enlarge upon their initial work to pregnant women and their babies.

Their future research may also offer insights into how probiotics might be effective in mitigating the effects of stress. At present it is too early to predict whether they may have any impact.


Dr Gur stresses that the message from the study should not be taken to mean that mothers are responsible for negatively affecting the mental health of their children. Rather we should focus on the importance of optimal mental health in general, and especially during pregnancy.

"As a psychiatrist who treats pregnant women, if you're stressed, anxious or depressed, I think pregnancy is a prime time for intervention," Gur said. "And what's good for mom is good for the baby".

Source: Medindia

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