Prenatal Stress is Linked to Gut Microbes in Infants

Chronic psychological stress in mothers during pregnancy and elevated cortisol levels in hair are associated with the composition of the infant’s gut microbiota, according to a publication by the FinnBrain research project at the University of Turku, Finland. The findings contribute to a better understanding of how prenatal stress may be related to infant growth and development.

Investigating the Role of Gut Microbes as Stress Mediators

Prenatal stress may be associated with infant growth and development. However, the mechanisms underlying this association are not yet fully understood. “We were able to show that chronic psychological stress in the mother and elevated cortisol concentrations in the hair during pregnancy are associated with the composition of the gut microbiota of infants, but not with its diversity,” says PhD student Anna Aatsinki.

The study used hair cortisol analysis to measure the average concentration of the stress hormone cortisol over several months. In addition, the mother’s symptoms were assessed three times during pregnancy. The gut microbiota of the infants was analyzed at an early age of 2.5 months using next-generation sequencing. Previous similar studies have focused on animals, and two smaller studies have been conducted on humans, making this study, with 399 mothers and their infants, the most comprehensive worldwide to date. The results provide important new insights into this phenomenon. In addition, this study confirmed previous observations.

Both Proteobacteria and Lactobacillus are common gut microbes in infants. For example, the researchers found that chronic psychological stress in the mother during pregnancy was associated with an increased frequency of Proteobacteria genera in the microbiota of infants. In addition, chronic psychological symptoms were associated with a lower frequency of the Akkermansia genus, which is considered beneficial to health, at least in adults. According to Aatsinki, it was also interesting that low cortisol concentrations were associated with an increased frequency of Lactobacillus in the gut microbiota of infants. Lactobacillus bacteria are considered beneficial to health.

Important Questions Remain

However, Proteobacteria also contain species that can cause inflammation in the body. Proteobacteria may also be associated with the child’s risk of disease later in life. Therefore, the researchers believe it is important to investigate how the observed changes are related to the child’s later development. “Our study does not explain the causal relationship or whether prenatal psychological stress is associated with differences in the metabolites of microorganisms or, for example, in the function of the immune system. In other words, important questions remain to be answered,” emphasizes Aatsinki.

The study is part of the FinnBrain research project and its subproject on the gut-brain axis. The subproject, led by Docent Linnea Karlsson, a child and adolescent psychiatrist, is investigating how prenatal stress affects the development of the microbiota in infants and how gut microbes in infants influence later brain development. The University of Turku’s FinnBrain research project is investigating the combined influence of environmental and genetic factors on child development. Over 4,000 families are participating in the research project and will be followed from infancy well into adulthood.