The neonate is exposed to the maternal vaginal microbiota during birth, providing the primary source for normal gut colonization, host immune maturation, and metabolism. These early interactions between the host and microbiota occur during a critical window of neurodevelopment, suggesting early life as an important period of cross talk between the developing gut and brain. Changes in the vaginal microbiome are associated with effects on offspring gut microbiota and on the developing brain, according to a new study.