Early-Life NO₂ Exposure and developmental coordination disorder in Preschool Children: A Cross-sectional Study

Although air pollution is a potential neurotoxicant, evidence linking early-life nitrogen dioxide (NO₂) exposure to motor development remains inconsistent, and large-scale studies are limited. This cross-sectional study investigated associations of prenatal and postnatal NO₂ exposure with motor coordination performance and suspected developmental coordination disorder (DCD) risk among 105,280 children aged 3-5 years from Chinese National Cohort of Motor Development. Motor coordination was assessed using the Little DCD Questionnaire (LDCDQ). NO₂ exposure was estimated using a high-resolution satellite-based random forest model. Linear mixed-effects models and generalized linear mixed models with a binomial distribution were applied to evaluate associations with LDCDQ scores and suspected DCD risk, respectively. Per interquartile range (IQR) increase in NO₂ during the first trimester and from birth to 36 months, LDCDQ scores decreased by 0.20 (95% confidence interval [CI]: -0.08, -0.31) and 0.10 (95% CI: -0.02, -0.19), respectively. Odds ratios for suspected DCD were 1.07 (95% CI: 1.03, 1.11) for first-trimester exposure and 1.04 (95% CI: 1.004, 1.07) for birth-to-18-month exposure. Among three LDCDQ subdomains, general coordination showed the strongest association. Associations appeared to be stronger among boys. These findings suggest that early-life NO₂ exposure may adversely affect motor coordination development of preschoolers, though the modest effect sizes were observed.