There are growing concerns that **antibiotic use, especially early in life, may influence neurodevelopment**, the process by which the brain grows and matures. This concern arises mainly because antibiotics can disrupt the natural community of microbes—known as the microbiome—that live in our gut and play a crucial role in brain development and function.
From birth, humans acquire microbes from their mother and environment, which help shape the immune system and brain circuits. Studies in animals, particularly mice, have shown that when these microbes are altered or absent, brain development can be affected. For example, mice raised without normal gut bacteria show differences in brain regions that control stress, social behavior, and vital body functions. These changes can persist into adulthood, suggesting that early microbial exposure is critical for normal brain wiring.
Antibiotics, by killing or altering gut bacteria, can disrupt this delicate balance. In mouse studies, giving antibiotics shortly after birth permanently changed the composition of gut bacteria and influenced brain health later in life. Some research even suggests that these changes might reduce certain types of brain damage in genetically predisposed mice, but the effects vary by sex and genetic background, indicating a complex relationship between antibiotics, microbes, and brain development.
In humans, modern medical practices such as giving antibiotics around childbirth or performing Cesarean sections can disturb the natural transfer of microbes from mother to baby. Since about 40% of women in the U.S. receive antibiotics during childbirth and one-third of births are by Cesarean, this disruption is widespread. Researchers worry that these interventions might unintentionally affect the newborn’s brain development, potentially influencing stress responses and social behaviors later in life.
Beyond microbial disruption, infections during pregnancy that require antibiotic treatment can themselves impact neurodevelopment. For instance, infections causing preterm birth have been linked to brain abnormalities and developmental delays in infants. This highlights the delicate balance between treating infections to protect the mother and fetus and avoiding unintended consequences on brain development.
However, the evidence is not entirely one-sided. Large human studies have found no clear link between early antibiotic exposure and increased risk of autoimmune diseases or other long-term immune problems in children. This suggests that while antibiotics do alter the microbiome, their use when medically necessary is unlikely to cause major harm to neurodevelopment in most cases.
Still, chronic or unnecessary antibiotic use may lead to altered levels of neuromodulators—chemicals that influence brain signaling—through the gut-brain axis, potentially causing cognitive impairments or metabolic changes. This further supports the
