Prenatal exposure to PM2.5 and its constituents with children's BMI Z-score in the first three years: A birth cohort study

Background: Limited studies evaluated the effect of prenatal exposure to fine particulate matter (PM2.5) on childhood growth and no consensus reached yet. No study explored the effect of prenatal exposure to PM2.5 and its constituents on childhood growth in a region with high PM2.5 levels (>50 & mu;g/m3). The present study aimed to examine the association of prenatal exposure to PM2.5 and its constituents with children's BMI Z-score in the first three years. Methods: The present study was based on a birth cohort in Beijing, China, involving 15,745 mothers with their children who were followed to three years old. We estimated prenatal PM2.5 and its constituents [organic carbon (OC), elemental carbon (EC), sulfate (SO4 2  ), nitrate (NO3  ), and ammonium (NH4+)] concentrations based on residential addresses at birth. Height (or length) and weight of children were repeatedly measured, and body mass index (BMI) Z-score was calculated at one, two, and three years old. Generalized linear regression and generalized estimating equation were used to examine the associations between prenatal exposure to PM2.5 and its constituents with BMI Z-score in the first three years.Results: Prenatal exposure to PM2.5 and its constituents was generally associated with higher BMI Z-score of children aged one, two, and three years. One IQR increase of PM2.5, OC, EC, NO3 , NH4+, and SO42 (21.30 & mu;g/m3, 11.52 & mu;g/m3, 2.40 & mu;g/m3, 8.28 & mu;g/m3, 2.42 & mu;g/m3, and 8.80 & mu;g/m3, respectively) was associated with 0.13 (95% CI: 0.10, 0.16), 0.24 (95%CI: 0.19, 0.29), 0.12 (95%CI: 0.09, 0.16), 0.13 (95%CI: 0.09, 0.17), 0.11 (95%CI: 0.08, 0.13), and 0.24 (95%CI: 0.19, 0.30) increase in BMI Z-score from one to three years old, respectively.Conclusion: The study suggested that prenatal exposure to PM2.5 and its constituents was associated with higher BMI Z-score of children in the first three years. Public health policy for controlling harmful PM2.5 constituents should be developed to promote child health.