Traffic-related air pollution and birth weight: the roles of noise, placental function, green space, physical activity, and socioeconomic status (FRONTIER)

Background and aim: FRONTIER aims to study the impact of maternal exposure to traffic-related air pollution (TRAP) on fetal growth while disentangling the effects of noise, elucidating the role of placental function as an underlying mechanism; and exploring the potential of greenspace to mitigate it. Methods: FRONTIER has established a new pregnancy cohort of 1,086 pregnant women in Barcelona (BiSC), Spain. Fetal growth was characterized by anthropometric measures at birth together with ultrasound-based measures of fetal development. We are integrating objective data on time-activity patterns with a hybrid modeling framework combining dispersion and land use regression models and campaigns of personal and home-outdoor air pollution monitoring to estimate maternal exposure level and inhaled dose of NO2, PM2.5, and PM2.5 light absorption and contents at the main microenvironments (home, workplace, and commuting routes). We are assessing maternal exposure to noise by integrating measurements at participants’ home-outdoor using noise monitors together with modeled microenvironmental noise levels and data on noise sensitivity, annoyance, and protections against noise. We will develop single- and multi-pollutant models to evaluate the impact of air pollution exposure and inhaled dose on fetal growth and the mediatory role of placental function. Results: BiSC mothers had an average age of 34.8 years with 31.1% having high school education and less and 73.6% having European origin. The mean (SD) of the first and third trimester measured personal NO2 levels were respectively 31.9(11.7) and 31.0(12.1)μg/m3 for the pre-pandemic period and 26.6(10.9) and 25.1(12.1)μg/m3 for the pandemic period. The mean (SD) of measured home-outdoor noise levels (LAeq,24h) was 61.5 (6.7)dB(A). 49.2% of newborns were girl and the mean (SD) of birthweight was 3276.8 (508.2)g The analyses are still ongoing. Conclusions: FRONTIER will provide a robust and comprehensive evaluation of the impact of TRAP exposure on fetal growth using high-resolution exposure data.