Prenatal and Postnatal Ambient Air Pollution Exposure and Weight Growth Trajectories in Early Childhood

Abstract

Background: Air pollution exposure during pregnancy has been positively associated with both low birth weight and higher body mass index later in life. The relationship between perinatal air pollution exposure and weight growth trajectories in early childhood, and the interaction with birth weight has yet to be studied.Methods: We combined electronic medical record (EMR) with survey data collected from caregiver-child dyads enrolled in the ethnically diverse Boston-based Children’s HealthWatch cohort (n=4,797). Geocoded residential address at each EMR entry was linked to daily 1 km2 PM2.5 predictions. We examined the association between pre- and postnatal (12-month averaging period) PM2.5 exposure and sex-specific weight (kg) growth trajectories from birth to age six, using piecewise linear and polynomial mixed models.Results: Mean prenatal and postnatal PM2.5 concentrations were similar between males (prenatal: 9.6 ±1.2 µg/m3; postnatal: 7.9 ±0.9 µg/m3) and females (prenatal: 9.5 ±1.2 µg/m3; postnatal: 7.9 ±1.0 µg/m3). Females with prenatal PM2.5 above the median (9.5 µg/m3) had significantly (p<0.05) higher weights versus females with prenatal PM2.5 below the median from 0-6 years of age (e.g. 0.16 kg higher at 24 months, 0.62 kg higher at 60 months). The association was similar among low birth weight (LBW) (< 2500 g) females (13.3% LBW). Conversely, males with prenatal PM2.5 above the median had lower weights (e.g. -0.17 kg at 24 months, -0.72 kg at 60 months) than males with prenatal PM2.5 below the median. Male weight trajectories did not differ by birth weight strata (14.1% LBW). Weight trajectories were not associated with postnatal PM2.5.Conclusions: Studying growth trajectories provides an opportunity to understand the life course impact of pre and postnatal air pollution. The findings demonstrate the complex association between environmental exposures and childhood weight gain and that the mechanism of sex-specific effects require additional research.