The impact of perinatal exposure to ambient air pollution on childhood body mass index trajectories

Evidence on the impact of perinatal ambient air pollution on childhood obesity remains inconsistent. This study investigated the associations between perinatal exposure to ambient air pollution and childhood body mass index (BMI) trajectories using a birth cohort (n = 24200) recruited in 2005 and followed at 0.5, 1.5, 3, and 5.5 years of age. Questionnaires were administrated to assess risk factors and anthropometric data. We used group-based trajectory modeling to identify BMI trajectories. Weighted quantile sum regression was used to determine the associations between BMI trajectories and exposure. Among the 21205 children included for analysis, trajectories were split into three-high-and-increasing, high-normal, and low-normal trajectory-at the age of 0.5 till 1.5 and between boys and girls. Average BMIs of children aged 5.5 for high-and-increasing, high-normal, and low-normal trajectory were 22.80, 17.32, and 15.16 kg/m² for boys and 21.42, 16.80, and 14.75 kg/m² for girls. A decile increase in air pollutant mixtures (PM_2.5, PM_2.5-10, and redox-weighted oxidant capacity combining ozone and nitrogen dioxide) during the first trimester and the first three months postpartum increased the risks of membership in high-and-increasing trajectory relative to the combining group of normal trajectories by 7 % and 8 % (adjusted odds ratio, 1.07 and 1.08; 95 % confidence interval, 1.04-1.11 and 1.05-1.10). The magnitudes of weights associated with PM_2.5-10 and redox-weighted oxidant capacity were greater than those of PM_2.5. These findings underscore the importance of minimizing perinatal exposure to ambient particulate matter and oxidant pollutants to help mitigate the risk of childhood obesity.