Associations between preconceptional and gestational ozone exposure and early infant neurodevelopment: A birth cohort study

• Preconceptional ozone exposure was associated with lower early infant neurodevelopmental scores. • Late-pregnancy ozone exposure was associated with poorer motor and social development in early infancy. • Associations varied across exposure windows, highlighting potentially sensitive early-life periods. • Adverse neurodevelopmental associations were observable as early as two months of age. Air pollution is a significant environmental risk factor linked to neurodevelopmental disorders and cognitive impairments. Most research focuses on particulate matter, while studies on gaseous pollutants like ozone and preconceptional exposures are limited. Data from 9,869 mother-child dyads in the Beijing Birth Cohort Study (BBCS) were used. Ozone and six particulate pollutants were obtained from the Tracking Air Pollution in China (TAP) database, a nationwide spatiotemporal air pollution modeling platform of China mainland. Neurodevelopmental outcomes at 2 months were assessed using the Ages and Stages Questionnaires, Third Edition (ASQ-3). Multivariable linear regression models estimated the effects of ozone exposure on ASQ scores, stratified by sex. Preconceptional ozone exposure (per 10 μg/m³ increase) was negatively associated with gross motor (β= -0.16, P =0.003), communication (β= -0.20, P =0.03), personal-social (β= -0.18, P =0.02), and problem-solving (β= -0.20, P =0.02) scores in all infants. Third-trimester ozone exposure was associated with lower fine motor scores (β= -0.14, P=0.04) and personal-social scores (β= -0.14, P=0.02). These associations remained robust after adjustment for co-exposure to fine particulate matter and its components. Sex-stratified analyses revealed boys were more sensitive to late pregnancy ozone exposure, while girls were more sensitive to preconceptional exposure. Preconceptional and gestational ozone exposure was associated with lower cognitive and motor function scores in infants, highlighting the potential importance of early-life exposure windows for neurodevelopment and informing future mechanistic research and public health prevention strategies.