Prenatal exposure to PM2.5 constituents and weight growth trajectory from in utero to three years: a birth cohort study

Early-life growth from in utero to early childhood plays a critical role in shaping long-term health, yet the impact of prenatal PM 2.5 constituent exposure on weight growth trajectories remains unclear. We included 16,372 mother-child pairs from a Chinese birth cohort. Prenatal PM 2.5 and its constituents [organic carbon (OC), elemental carbon (EC), ammonium (NH 4 + ), nitrate (NO 3 − ), and sulfate (SO 4 2− )] exposures were estimated using a modified Community Multiscale Air Quality model. A latent class growth model was employed to explore weight growth trajectories from 20 gestational weeks in utero, birth, 6 months, 1, 2, and 3 years. Associations were analyzed using multinomial logistic regression and quantile-based g-computation (QGC). Three distinct weight Z-score growth trajectories were identified: normal (26.6% in boys, 17.7% in girls), approaching-risk-of-overweight (63.0%, 66.7%), and risk-of-overweight (10.4%, 15.6%). An interquartile range increase in prenatal exposure to PM 2.5 was associated with a 13.5% higher risk of the approaching-risk-of-overweight trajectory (risk ratio [RR]=1.135, 95% CI: 1.050, 1.228) and a 23.2% higher risk of the risk-of-overweight trajectory (RR=1.232, 95%CI: 1.103, 1.376). Similar associations were observed for OC, EC, NH 4 + , and SO 4 2− , with stronger effects for the risk-of-overweight trajectory. In QGC models, each quintile increase in prenatal mixture exposures of PM 2.5 constituents had RRs of 1.354 (95%CI: 1.104, 1.662) for approaching-risk-of-overweight and 1.606 (95%CI: 1.192, 2.161) for risk-of-overweight, respectively. These findings highlight the adverse impact of prenatal PM 2.5 and constituent exposures on early-life growth, and underscore the need to reduce prenatal PM 2.5 exposure to promote healthy growth trajectories in early childhood.