In recent years, scientists have increasingly focused on the gut microbiome—the vast community of bacteria living in our digestive system—and its wide-ranging influence on human health.

Research has linked gut bacteria to immune function, stress response, mental well-being, and susceptibility to autoimmune conditions such as rheumatoid arthritis and type 1 diabetes. Now, a study published in The Journal of Immunology is shedding new light on how the maternal microbiome may play a role in early brain development.

The World Health Organization describes autism as a group of neurodevelopmental conditions that affect communication, social interaction, and behavior, often alongside other conditions such as anxiety, epilepsy, or attention difficulties. Abilities and challenges vary widely from person to person.

According to the study, the mother’s gut microbiota may influence developmental pathways more strongly than the child’s own microbiome during early stages of life. Lead researcher John Lukens, PhD, from the University of Virginia School of Medicine, explained that gut bacteria can affect how the immune system responds to stress, infection, and inflammation—factors that may indirectly shape brain development.

Researchers focused on a molecule produced by the immune system called interleukin-17a (IL-17a). This cytokine is known to play a role in immune defense and inflammatory conditions, and emerging evidence suggests it may also influence neural development during pregnancy.

In the study, scientists examined mice with different gut microbiota compositions. One group carried bacteria associated with stronger inflammatory responses, while a control group did not. When IL-17a activity was suppressed early on, both groups displayed typical behavior. However, as the mice developed naturally, those exposed to higher inflammatory signals later showed behavioral patterns commonly used in animal research to model neurodevelopmental differences.

To further explore the connection, researchers transferred gut bacteria from one group of mice to another through fecal microbiota transplantation. The second group later exhibited similar behavioral changes, reinforcing the potential role of gut-driven immune signaling.

While the findings are limited to animal models, researchers emphasize that the study provides a foundation for future human research, not definitive conclusions. Lukens noted that the next step is identifying maternal microbiome characteristics that may correlate with developmental outcomes, while stressing the importance of safety.

Manipulating immune responses during pregnancy carries risks, researchers caution, as pregnancy requires a delicate balance of immune regulation. Any future therapies would require extensive testing and careful clinical oversight.