Association of prenatal exposure to PM2.5 and its chemical constituents with early childhood obesity: A population-based study.

A growing body of evidence links gestational fine particulate matter (PM2.5) exposure to elevated childhood obesity risk, yet research on the combined impacts and respective contributions of different PM2.5 chemical constituents remains limited. This large population-based prospective study involved 339,435 mother-child pairs from Liaoning Province, China. Prenatal exposure to PM2.5 and five major chemical constituents (organic matter (OM), black carbon (BC), ammonium (NH₄⁺), nitrate (NO₃⁻), sulfate (SO₄²⁻)) was estimated using high-resolution atmospheric reanalysis data. Quantile g-computation (QGC) was used to investigate the joint associations of PM2.5 chemical constituent mixtures and the relative contribution of each constituent with childhood overweight/obesity (OwOb) risk across the first two years of life. In single-pollutant models, prenatal exposure to PM2.5 total mass (per interquartile range, odds ratio (OR) = 1.050, 95% confidence interval (CI): 1.036, 1.064) and four of the five chemical constituents (OM: OR = 1.058, 95% CI: 1.043, 1.072; NH₄⁺: OR = 1.048, 95% CI: 1.035, 1.062; NO₃⁻: OR = 1.048, 95% CI: 1.033, 1.064; and BC: OR = 1.033, 95% CI: 1.020, 1.047) were positively associated with increased risks of offspring OwOb. A one-quartile increase in the mixture of multiple PM2.5 chemical constituents was associated with increased OwOb risk (OR = 1.063, 95% CI: 1.050, 1.076), with OM (54.1%), NH₄⁺ (34.4%), and NO₃⁻ (11.5%) acting as major contributors to the overall mixture effects. These findings underscore that regulating key PM2.5 chemical constituents is a vital public health strategy to mitigate the adverse effects of prenatal air pollution on children's metabolic health.