Early antibiotic exposure may put infants at risk of developmental delays

Exposure to antibiotics within the first 3 months of life carries a modest increase in the risk of global developmental delays, especially in motor skills, cognitive function, and communication abilities, according to a study.

In a cohort of 1,848,841 children (median age 4.94 years) who participated in the Korean National Health Insurance System and the National Health Screening Program for Infants and Children, those with antibiotic exposure in their first 3 months of life (23 percent of the population) had 3-percent greater odds of developmental delay during the preschool period (odds ratio [OR], 1.03, 95 percent confidence interval [CI], 1.00–1.17). This association followed a dose-response pattern, such that a higher OR was observed with longer than shorter antibiotic courses (<7 days: OR, 1.03, 95 percent CI, 0.99–1.07; ≥7 days: OR, 1.05, 95 percent CI, 1.00–1.10).  [BMJ Paediatr Open 2025;9:e003361]

Among the six developmental domains examined, significant associations were observed for gross motor (OR, 1.08, 95 percent CI, 1.04–1.13), fine motor (OR, 1.09, 95 percent CI, 1.05–1.13), cognition (OR, 1.08, 95 percent CI, 1.04–1.13), and communication (OR, 1.08, 95 percent CI, 1.04–1.12).

Subgroup analyses indicated that the likelihood of global developmental delay associated with early-life antibiotic exposure was particularly pronounced among high-risk infants: those with any history of hospitalization (OR, 1.09, 95 percent CI, 1.01–1.17), those with complex chronic conditions (OR, 1.48, 95 percent CI, 1.31–1.68), and those who were born preterm  (OR, 1.35, 95 percent CI, 1.31–1.68).

The findings warrant judicious antibiotic prescription for infants under 90 days old, as well as the limitation of the duration of use whenever possible, the investigators said.

“While it is not entirely clear whether the observed findings in our study are mediated by the infections prompting antibiotic prescriptions or the effects of the antibiotics themselves, various additional analyses even after multivariable adjustment suggest that at least a portion of the adverse effects can be attributed to the antibiotics themselves,” they noted.

Antibiotics can exert a negative effect on the intestinal microbiota, with prior studies linking antibiotic intake to gut dysbiosis. This imbalance in the different bacteria in the gastrointestinal tract has been shown to result in worse cognition and negative valence system in vivo and in increased fear reactivity and negative reactivity in infants. [Front Neurosci 2023;17:1237177; Signal Transduct Target Ther 2024;9:37]

The investigators also acknowledged several study limitations, including the lack of information on parental education and age, maternal infection history, prenatal antibiotic use, gestational age in weeks, and detailed information on cumulative antibiotic use, among others.

“Nevertheless, the study makes a significant contribution to understanding the possible negative effects of antibiotics on child development,” they said.