Lee YH, et al. - Experts aspired to explore whether prenatal bacterial infection can be correlated with cognitive impairments in early childhood. Using the Wechsler Intelligence Scale for Children, IP weighting was applied for both treatment and censoring to estimate the impacts of maternal bacterial infection during pregnancy on mean IQ scores calculated at age 7. Candidates were part of a population-based pregnancy cohort enlisted in the Boston and Providence sites of the Collaborative Perinatal Project between 1959 and 1966 (n = 11,984). Using IP weights estimated via generalized boosted models, average treatment effects (ATE) and average treatment effects on the treated (ATT) were calculated. Among offspring exposed to multi-systemic bacterial infection during pregnancy, ATE- and ATT-weighted mean IQ scores were lowest and highest for those unexposed. An association was found between prenatal bacterial infection and cognitive impairments at age 7. Associations are highest in the third trimester and among males for more severe infections. Intervention in public health targeting bacterial infection in pregnant women can help to improve offspring's cognitive development.