Prenatal exposure to PM2.5 constituents and children’s growth trajectory in the first two years: a birth cohort study

Abstract

BACKGROUND AND AIM: Limited studies on the associations of prenatal exposure to fine particulate matters (PM2.5) with children’s growth reported inconsistent results. No study evaluated the effects of specific constituents of PM2.5 on children’s growth trajectory, which may contribute to discrepancies among PM2.5 studies. We aimed to examine the association of prenatal exposure to PM2.5 constituents and children’s growth trajectory in the first two years. METHODS: The study was based on a birth cohort(2014-2017) in China, involving 18,667 mothers with their children who were followed to two years old. We estimated prenatal PM2.5 constituents [organic carbon(OC), elemental carbon(EC), sulfate(SO42-), nitrate(NO3-), and ammonium (NH4+)] concentrations based on maternal home addresses. Height(or length) and weight of children were repeatedly measured at the age of 3,6,9,12,18,24 months. We calculated body mass index (BMI) Z-score based on the WHO Standards. Latent class growth modeling was used to identify children’s BMI Z-score trajectory. Multinomial logistic regression was used to examine the association of prenatal exposure to PM2.5 constituents with children’s growth trajectories. RESULTS:Three BMI Z-score trajectories were identified: stable trajectory (n=15265,81.9%), decreased trajectory(n=2130,11.4%), and increased trajectory(n=1234,6.6%). Compared with stable trajectory, an interquartile range (IQR) increase in prenatal exposure to PM2.5, NH4+, and NO3- was associated with 0.847[95% confidence interval(95%CI):0.744,0.965], 0.806(95%CI:0.710,0.915), and 0.677(95%CI: 0.603,0.761) lower risk of increased trajectory, respectively. An IQR increase in prenatal exposure to OC and SO42- was associated with 1.395(95%CI:1.236,1.575) and 1.562 (95%CI:1.324,1.842) higher risk of increased trajectory, respectively. The results were robust in two-pollutant models. We did not observe significant associations between prenatal exposure to PM2.5 constituents and risk of decreased trajectory. CONCLUSIONS:The study suggested that prenatal exposure to PM2.5 and its constituents was associated with risk of children’s increased growth trajectory in the first two years. Public health policy on regulation of harmful PM2.5 constituents should be developed to protect early-life health of children. KEYWORDS: particulate matters, constituents, body mass index, growth trajectory, children