Maternal Microbes Influence Early Brain Development, New Research Finds

Recent research from Michigan State University highlights the crucial role that maternal microbes play in shaping early brain development. The study, published in the journal Hormones and Behavior, emphasizes how exposure to microbes during the perinatal period can impact critical brain regions responsible for stress regulation, social behavior, and vital bodily functions.

Using a mouse model, scientists demonstrated that microbial exposure immediately after birth influences brain structure development and possibly begins in the womb. Because mice share significant biological similarities with humans, they serve as an effective model for studying the influence of microbes on brain development. This research is especially relevant in the context of modern obstetric practices, such as antibiotic use during childbirth and cesarean sections, which can disrupt maternal microbial transmission. In the United States, about 40% of women receive antibiotics around childbirth, and approximately one-third of births occur via cesarean, potentially impacting the natural microbiome transfer.

Lead researcher Alexandra Castillo Ruiz explained that at birth, a baby is colonized by microbes as it passes through the birth canal—a process that coincides with key developmental events in the brain. Her team focused on a vital brain area called the paraventricular nucleus of the hypothalamus (PVN), which regulates stress responses, blood pressure, water balance, and social behaviors. Previous studies showed that germ-free mice, which lack microbes, presented with increased neuron death in the PVN during early development.

In experiments involving cross-fostering, germ-free newborn mice raised by microbe-rich mothers exhibited fewer neurons in the PVN shortly after birth, regardless of when microbes were introduced. Notably, adult germ-free mice also had reduced neuron numbers in this brain region. Dr. Castillo-Ruiz concluded that microbes are integral in shaping this essential brain area and that their effects may begin in the womb via signaling from maternal microbes. The findings underscore the importance of recognizing microbes as partners in early development, aiding in the construction of healthy brains from the very beginning.

This study advances our understanding of how maternal microbiomes influence neurodevelopment and highlights the potential long-term consequences of disrupting microbial transfer during delivery.