A population-based cohort study of traffic congestion and term birth weight using vehicle telematics data

Abstract

Background and Aim: Over 11 million Americans reside within 150 m of a major highway, an area of high air pollution exposure. Traffic congestion further contributes to this problem but has not been evaluated in epidemiological studies to-date. We hypothesize that degraded air quality due to traffic congestion will have an adverse impact on infant birth weight. Methods: Using a population-based birth cohort in 2015-2016 for the State of Texas, we limited our study population to addresses within 1,000 m of a road in this database. We calculated traffic congestion around each geocoded maternal address at delivery for 100 m, 300 m, and 500 m buffer distances. We leveraged novel congestion and vehicle volume measurement data from the Texas Most Congested Roads database, which contains measurements of traffic volume, delay, and emissions from connected vehicle and device data. We used linear regressions to evaluate the association between traffic congestion and term birth weight, adjusting for sociodemographic characteristics and vehicle volume. Results: Among 580,992 births, we find consistent negative associations between traffic congestion and term birth weight. We observed a 15.8 g reduction in term birth weight (95% CI: -20.5, -11.1) among the highest quintile of delay exposure at 500 m compared to births with no delay exposure in this buffer distance. Results are similar, though attenuated, for truck-specific congestion. When we calculate excess vehicle emissions from congestion, we observe a -17.6 g reduction in term birth weight (95% CI: -21.4, -13.9) when comparing the highest and lowest quintiles. Conclusion: Our study provides important new evidence that traffic congestion is associated with adverse infant health outcomes, in addition to total traffic volumes on nearby roads. Therefore, programs to reduce traffic congestion may have positive co-benefits for infant health with respect to birth weight. Keywords: traffic-related air pollution, infant health, birth weight