Maternal gut bacteria found to communicate with foetus

A new study led by the University of Oulu has shown that nanoparticles originating from maternal gut bacteria are present in amniotic fluid. This is a previously unknown mechanism of communication between the maternal gut microbiome and the foetus.

The detected nanoparticles are extracellular vesicles, which contain molecules derived from cells such as proteins, DNA, RNA and metabolic products. These nanoparticles play an important role in bacterial communication.

The study, which involved 25 mothers who gave birth by Caesarean section at Oulu University Hospital, revealed that the nanoparticles found in amniotic fluid and maternal faeces were similar in terms of bacterial species and content. The study was refined in an experimental animal model, where it was found that extracellular vesicles isolated from human maternal faeces migrate to the foetus.

The results, published in the journal Microbiome, may provide an answer to the question that has long puzzled the scientific community: whether a healthy foetus is exposed to bacteria during pregnancy and whether the foetal environment has its own microbiota.

“According to our study, in healthy pregnancy, nanoparticles secreted by maternal gut bacteria migrate to the amniotic fluid, containing molecules derived from bacteria,” said doctoral researcher Anna Kaisanlahti. “The vesicles do not cause infections like whole bacteria. Thus, the foetus safely becomes acquainted with the mother’s normal gut microbes before birth. The mechanism we have found is likely to play a significant role in the development of the foetal immune system during pregnancy.”

The nanoparticles produced by maternal gut bacteria may be important for the development of the foetal immune system. They may safely prepare the foetus for the moment of birth, when the foetal intestine quickly acquires its own microbiota. The finding thus opens doors for further research.

“It would be interesting to study how the communication between the maternal gut bacteria and the foetus during pregnancy affects the child’s health later in life,” Kaisanlahti said.

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