Prenatal Exposure To Traffic-Related Air Pollution And Infant Neurobehavior

Abstract

Prenatal exposure to traffic-related air pollution (TRAP) has been associated with adverse neurobehavioral outcomes, but has not been investigated during early infancy. In a cohort of 352 mother/infant pairs in the Health Outcomes and Measures of the Environment (HOME) Study, we examined associations between prenatal exposure to TRAP and infant neurobehavior. TRAP exposure was estimated with a land use regression model using the mother's home address at 20 weeks gestation, with TRAP dichotomized at the median of 0.36 µg/m3. Infant neurobehavior was assessed at 5 weeks of age using the NICU Network Neurobehavioral Scale (NNNS), a comprehensive neurobehavioral assessment for young infants. Higher scores are favorable for habituation, attention, regulation, and quality of movement scales, and lower scores are favorable for excitability, handling, lethargy, nonoptimal reflexes, asymmetry, hypertonicity, hypotonicity, and stress/abstinence scales. For arousal, an optimal score is moderate. With regard to arousal scores, a range of 1.00 to 6.42 is possible, and in this cohort the distribution indicated that there were primarily two main groups of infants in our study: moderate (score 2.4-4.8) and high (score 4.8-6.0), so arousal was also examined dichotomously. Potential covariates in multivariable models included household income, race, and marital status. Infant's age and sex were retained in all models as a priori confounders. The only individual NNNS scale significantly associated with TRAP was arousal. Higher TRAP was associated with an increased risk for a high (vs. moderate) arousal score, and this remained significant after adjusting for relevant covariates (aRR 1.4; 95% CI 1.3-1.6). High arousal scores indicate infants who are easily aroused to fuss and cry during an exam, and who are highly active while being handled and while left alone. The possibility that deleterious impacts of TRAP on neurobehavior may be manifest at birth deserves future study.