Early-life exposure to particulate matter and green spaces: Associations with infant growth

Abstract

Early-life exposure to air pollution and green space may influence child growth, but evidence across multiple anthropometric indicators is limited. We examined whether perinatal exposures to particulate matter (PM) and residential green space are associated with longitudinal changes in body mass index (BMI), length, and head circumference (HC). In 119,110 Flemish children, BMI-, length-, and HC-for-age z-scores were derived from wellbaby clinic data. Perinatal PM10 and PM2.5 concentrations were estimated using the RIO detrended-kriging interpolation model. Municipal green space was categorized into low, high, and total vegetation. Mixedeffects models incorporating a 5-degree-of-freedom natural cubic spline for child age, exposure-by-age spline interaction terms, and child-level random intercepts and age slopes were used to assess associations per interquartile-range (IQR) contrast in exposure, adjusting for key covariates and co-exposures. Associations varied nonlinearly across child age and growth outcome.At 12 months, an IQR increase in PM10 or PM2.5 concentration was associated with lower HC-for-age z-scores (PM10: B = -0.0499; 95% CI: -0.0606; -0.0393; PM2.5: B = -0.0645; 95% CI: -0.0771; -0.0518), and inverse associations were observed between 6 and 24 months. Associations of PM with BMI-for-age and length-for-age changed direction across age. Total and high green-space exposures were associated with higher BMI-for-age and length-for-age at several ages, whereas associations with HC were inconsistent across green-space measures and ages. Low green-space exposure was associated with lower HC-for-age and length-for-age at several ages. Estimates were small, and urbanicity did not consistently modify associations. Most nominally significant associations remained significant after false-discovery-rate correction; exceptions were PM2.5 exposure at 2 months and high and total green-space exposure at 12 months in relation to length-for-age. Perinatal air pollution and green space exposures showed small, nonuniform associations with early childhood growth that varied across child age and anthropometric outcomes.