Prenatal exposure to residential PM2.5 and its chemical constituents and weight in preschool children: A longitudinal study from Shanghai, China

Background: Studies have reported that prenatal exposure to fine particulate matter (PM2.5) might be associated with adverse birth outcomes in offspring. However, evidence with regard to the effects of prenatal exposure to PM2.5 and, especially, its main chemical constituents on offspring's weight in childhood is limited and inconsistent. Objectives: The present study aimed to examine associations of prenatal exposure to PM2.5 total mass and its chemical constituents in each trimester with children's weight from birth to 6 years of age using data from Shanghai-Minhang Birth Cohort Study. Methods: A total of 1,084 mother-infant pairs were included with both PM2.5 exposure data and at least one measurement of weight and height. Weight-for-Length (WLZ), BMI-for-Age (BMIz), and Weight-for-Age (WAZ) z-scores were generated according to the World Health Organization guidelines. Exposure to PM2.5 total mass and its chemical constituents [organic carbon (OC), black carbon (BC), ammonium (NH4+), nitrate (NO3-), sulfate (SO42-), and soil dust (SOIL)] during pregnancy was estimated from a satellite based modelling framework. We used multiple informant model to estimate the associations of trimester-specific PM2.5 total mass and its specific constituents concentrations with WLZ/BMIz and WAZ of offspring at birth and 1, 4, and 6 years of age. Results: In multiple informant model, we observed consistent patterns of associations between exposure to PM2.5 total mass, OC, BC, NH4+, NO3-, and SO42- during the 2nd and 3rd trimesters and decreased WLZ/BMIz and WAZ at 1, 4, and 6 years of age in boys. We observed associations between prenatal exposure to PM2.5 total mass, NH4+, and NO3- during the 1st and 2nd trimesters and increased WLZ/BMIz and WAZ in girls at birth. However, there were null associations at 1 and 4 years of age and inverse associations at 6 years of age. Conclusions: Prenatal exposure to PM2.5 total mass and its main chemical constituents was associated with decreased weight in boys from 1 to 6 years of age, with increased weight at birth and decreased weight at 6 years of age in girls. Our findings suggest that prenatal exposure to PM2.5 and its chemical constituents may have a lasting effect on offspring's weight in childhood.