Analysis of 2.5 million Korean mother-child pairs reveals that prenatal exposure to proton pump inhibitors and H2 receptor antagonists correlates with elevated rates of autism spectrum disorders and ADHD in offspring. The population-based cohort tracked children through age 10, finding hazard ratios of approximately 1.3 for autism and 1.4 for ADHD among exposed children compared to unexposed controls. This finding adds to mounting evidence that the maternal microbiome and gastric environment during pregnancy may influence fetal neurodevelopment through gut-brain axis pathways. Previous research has established links between altered maternal gut bacteria and offspring behavioral outcomes in animal models, while human studies have suggested associations between prenatal antibiotic exposure and neurodevelopmental differences. The mechanism likely involves changes in maternal nutrient absorption, particularly B vitamins and folate critical for neural tube development, alongside shifts in beneficial bacterial populations that produce neuroactive metabolites. However, the observational design cannot establish causation, and confounding factors like maternal stress or underlying conditions requiring acid suppression may contribute. The clinical implications remain nuanced—women with severe reflux shouldn't avoid necessary treatment, but the lowest effective doses during pregnancy appear prudent given these population-level associations.