Short-Term Exposure to Urban Air Pollution and Influences on Placental Vascularization Indexes

BACKGROUND It has been widely demonstrated that air pollution can affect human health and that certain pollutant gases lead to adverse obstetric outcomes, such as preeclampsia and fetal growth restriction. OBJECTIVES We evaluated the influence of individual maternal exposure to air pollution on placental volume and vascularization evaluated in the first trimester of pregnancy. METHODS This was a cross-sectional study on low-risk pregnant women living in São Paulo, Brazil. The women carried passive personal NO2 and O3 monitors in the week preceding evaluation. We employed the virtual organ computer-aided analysis (VOCAL) technique using three-dimensional power Doppler ultrasound to evaluate placental volume and placental vascular indexes [vascularization index (VI), flow index (FI), and vascularization flow index (VFI)]. We analyzed the influence of pollutant levels on log-transformed placental vascularization and volume using multiple regression models. RESULTS We evaluated 229 patients. Increased NO2 levels had a significant negative association with log of VI (p = 0.020 and beta = -0.153) and VFI (p = 0.024 and beta = -0.151). NO2 and O3 had no influence on the log of placental volume or FI. CONCLUSIONS NO2, an estimator of primary air pollutants, was significantly associated with diminished VI and VFI in the first trimester of pregnancy.