Exposure to stress in the prenatal phase could lead to anxiety and cognitive problems in offspring that could continue into adulthood suggests new U.S. research on animal models.
Researchers from The Ohio State University exposed pregnant mice to stress to look at what the effect would be on both the mothers and the children.
To induce stress the pregnant mice underwent two hours per day for seven days of restraint, while another group of mice were left undisturbed to act as a control.
Gut bacteria were assessed using fecal samples from the mice.
The team found that stress appeared to change the makeup of the bacteria in the mothers' guts and placentas, as well as in the intestinal tracts of their female offspring, with the microbial changes even lasting into adulthood.
In addition, markers of inflammation increased in the mothers' placenta and the fetal brain and adult brains of the offspring, and levels of the protein brain-derived neurotrophic factor (BDNF), which helps support the growth and survival of brain neurons, decreased.
The team also observed that the offspring of stressed mothers fared worse in tests which assessed anxiety and cognitive health and had a lower ability to learn than female offspring of mice who were not exposed to stress during pregnancy, even though they were never stressed after birth.
Although the researchers also found interesting changes in the male offspring, the team are still working on that part of the study.
Commenting on what caused the health problems, Gur said, "We already understand that prenatal stress can be bad for offspring, but the mystery is how."
"More and more, doctors and researchers are understanding that naturally occurring bacteria are not just a silent presence in our body, but that they contribute to our health."
Gur added that microbes from a mother's gastrointestinal and reproductive tracts are the first to colonize in a developing fetus and in newborns, and as Gur and her colleagues found significant microbial changes to the placentas of the female offspring of stressed mice, these changes in microbes could have had an important influence on health, even before birth.
Gur also stressed that the findings do not mean that mothers are to blame for any mental illness in their children, but instead should be used an opportunity to talk more about the importance of mental health, both in general and 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," said Gur, "And what's good for mom is good for the baby."
The results of the study were presented by Gur on November 14 in San Diego at Neuroscience 2016, the annual meeting of the Society for Neuroscience.
