Can excessive antibiotic use in infancy cause developmental delays?
Antibiotics are powerful medicines that fight bacterial infections, but giving them too often to babies in their first year of life can disrupt the gut microbiome, which is the community of good bacteria that helps the body grow and stay healthy. This disruption, known as dysbiosis, may play a role in developmental delays by affecting brain and immune system growth.
Babies are born with a mostly empty gut that fills up with helpful bacteria from sources like breast milk and the environment during the first year. This time is key because the microbiome influences everything from digestion to how the brain develops. Studies show that antibiotics kill off both bad and good bacteria, leading to lower diversity in the gut. For example, children treated with antibiotics have fewer key bacteria like Faecalibacterium prausnitzii, Clostridium leptum, Bacteroides species, and Bifidobacteria such as B. bifidum, B. breve, and B. longum. These bacteria help produce short-chain fatty acids and support immune function, which are linked to normal neurological growth.
Researchers have found that early antibiotic use changes the microbiome in ways that last months or longer. In newborns, especially preterm ones, this can lead to imbalances that raise the risk of chronic issues. One study notes that altering the microbiome in infancy might contribute to neurological disorders like autism spectrum disorder. The first year is especially sensitive because it sets the stage for immune responses and brain wiring. Even short courses of antibiotics can reduce species richness and boost antibiotic-resistant genes, making recovery harder.
Breast milk helps protect against these problems by feeding good bacteria and blocking harmful ones like Streptococcus agalactiae, which causes infections. But antibiotics can override this natural protection, leading to inflammation and weaker gut barriers. Experts suggest using antibiotics only when truly needed, keeping courses brief, and choosing ones with less impact on the microbiome. Probiotics and prebiotics might help restore balance after treatment, though more research is needed for babies.
Preventing infections with vaccines could cut down on antibiotic needs altogether. For instance, avoiding early infections means fewer drugs and a healthier microbiome start. While direct proof linking antibiotics to specific delays like speech or motor issues is still emerging, the gut-brain connection is clear: a disrupted microbiome in infancy correlates with broader health risks, including developmental ones.
Sources
https://pmc.ncbi.nlm.nih.gov/articles/PMC12729859/
https://www.pnas.org/doi/10.1073/pnas.1717163115
https://spj.science.org/doi/10.34133/research.0558
