An international team of researchers found that gut microbiomes of 2-year-old children reflect the hardship experienced by their mothers during their own childhoods or pregnancy. This is the first research to document the intergenerational effects of adversity on the human gut microbiome.
The study, led by researchers from the University of California - Los Angeles (UCLA) builds on previous research which showed that prenatal stress affects vaginal and gut microbiomes. As babies get their first gut microbes through the mother’s birth canal, the latter's microbiomes are the foundation of their child’s, according to UCLA’s press statement. Previous studies have also revealed that stress experienced by the infant in the womb and the mother’s psychological distress affects their microbiomes. The study was published in the Proceedings of the National Academy of Sciences.
In 450 mother-child pairs in Singapore, the UCLA study looked at the effects of maltreatment on mothers during their childhoods, anxiety during pregnancy, and their children's exposure to stressful life events when they were two years old. The researchers also recorded any abuse or neglect that mothers experienced as children. Primary caregivers of the mothers were also contacted to consider any maltreatment they suffered in the first two years of their life.
The findings revealed that children whose mothers reported more anxiety during pregnancy had microbiomes wherein the microorganisms had populations of similar sizes, which is called “evenness”. Furthermore, the microbiomes of children who experienced stressful life events after birth also had less genetic diversity, according to the statement.
A previous study, in 2022, of study of wild geladas, a non-human primate that lives in Ethiopia, showed that the gut microbiome of a wild mammal exhibits clear and significant maternal effects both before and after weaning. According to this research, mothers' effects on the gut microbiome community of their children may last long after the child has stopped nursing, according to the press statement by Arizona State University
“There are a lot of questions around whether more diversity or evenness is better or worse when the gut microbiome is developing during childhood, so we don’t know if more is better at 2 years old,” said Francesca Querdasi, the new study’s lead author said in UCLA’s statement.
Querdasi also said the findings indicated that the gut microbiome could be interacting with the immune system differently after adversity. The brain–gut microbiome connection develops quickly during the first two to three years after birth, and the changes due to adversity could likely influence children’s socioemotional development.