Prenatal Air Pollution Exposure and Longitudinal Infant Weight Gain Trajectories

Abstract

BACKGROUND AND AIM: The prenatal period may play a critical role in childhood obesity development. We examined the association between prenatal nitrogen oxides (NOx) and nitrogen dioxide (NO2) exposure and weight trajectories from birth to 2-years-of-age among infants in the Maternal and Development Risks from Environmental and Social Stressors (MADRES) pregnancy cohort. METHODS: Participants were enrolled during pregnancy and their children were followed up to 2 years. Anthropometric measurements were collected using a combination of medical record abstractions and study-staff measurements (n=471 participants; n=4,287 observations). Residential exposure to NOx and NO2 were estimated as: 1) spatial interpolation from air quality monitoring stations (daily NO2, ambient background), 2) CALINE4 line source dispersion modeled contribution from nearby roadways (daily NOx, traffic-related), and predictions from a machine-learning based spatiotemporal model (weekly NO2 and NOx, R2=0.87, RMSE=2.80 ppb). Exposures were averaged across pregnancy accounting for variable gestation lengths. Sex-stratified quadratic growth curve models were used to assess the association between prenatal NO2/NOx exposure and infant weight trajectories. RESULTS:Prenatal spatiotemporal model predicted NO2 exposure was associated with infant growth trajectories for both sexes. Infants experienced the most rapid growth early on with an average deceleration in weight gain of 0.02 grams/day over the two-year period. Among females (n=243), a 1-SD increase (3.3 ppb) in NO2 exposure was significantly associated with growth acceleration of 0.001 grams/day (p=0.02) such that at 2-years-of-age, children exposed to higher prenatal NO2 weighed significantly more than lower-exposed individuals. Among males (n=228), the linear and quadratic parameters of growth were both statistically significant. However, by 2 years the trajectories converged and no significant differences in weight were observed. We found similar trends when examining NOx and ambient NO2 exposures. CONCLUSIONS:Our findings show prenatal NO2/ NOx exposure may play a role in childhood obesity, with more pronounced effects on weight gain in females. KEYWORDS: Air pollution, oxides of nitrogen, birth outcomes, children's environmental health