A new study published in *The Journal of Immunology* suggests a strong link between a mother’s gut microbiota and the development of autism in her offspring. “The microbiome can shape the developing brain in multiple ways,” said lead researcher John Lukens from the University of Virginia. He added that it influences how a child’s immune system responds to “infection or injury or stress.”

Central to this research is a molecule called interleukin-17a (IL-17a), which plays a role in infections and autoimmune diseases like psoriasis and multiple sclerosis. Importantly, IL-17a can also affect fetal brain development.

Researchers tested the effects of IL-17a using mice. Mothers with gut bacteria that triggered inflammatory responses via IL-17a gave birth to pups showing autism-like behaviors. However, when IL-17a was suppressed, these behaviors didn’t appear.

To confirm the gut link, scientists performed a fecal transplant from affected mice to unaffected ones. After the transplant, the new group also produced offspring with autism-like traits—highlighting the microbiome’s role.

Although this research is in early stages and focused on animals, it suggests maternal gut health may influence autism risk. Lukens emphasized that “IL-17a might be a single component in a much bigger picture.”