Effect of acute air pollution exposure on pregnant women's blood pressure: Insights from personal exposure assessment

• We assessed personal exposure during one week, 3 times during pregnancy • Measurement weeks were directly followed by a study visit to measure blood pressure • At visit 1, PM 2.5 and their OP were associated with a decreased heart rate • At visit 2, o-xylene and m-xylene were associated with a decreased heart rate • At visit 3, PM 2.5 was associated with an increased blood pressure Exposure to air pollution has been associated with adverse cardiovascular outcomes. Pregnant women may be especially vulnerable to air pollution due to physiological changes that affect blood pressure regulation. Traditional methods of estimating air pollution exposure based on home addresses and using either local monitoring stations, land use regression or dispersion models may not accurately capture individual exposure levels to explore its association with blood pressure. This study uses personal exposure to air pollutants to investigate short term associations with blood pressure outcomes at different stages of pregnancy. This study is based on data from the SEPAGES cohort. Blood pressure was measured during 3 visits throughout pregnancy, and air pollution exposure (benzene, toluene, ethylbenzene, o-xylene, m-xylene and p-xylene, nitrogen dioxide, fine particulates (PM 2.5 ), and PM 2.5 oxidative potential) was assessed using personal sensors during the week before blood pressure measurements. Multiple linear regressions were conducted for each outcome and pollutant, adjusting for confounding factors. 478 pregnant women were included. Around the 19th week, we found a lower heart rate and pulse pressure associated with elevated PM 2.5 levels and their oxidative potential. In the later stages of pregnancy, we observed higher diastolic blood pressure and mean arterial pressure as PM 2.5 concentrations increased. Nonetheless, these findings should be interpreted cautiously, as no consistent pattern emerges across timeframes and pollutants. Our study highlights the complex relationship between air pollution and blood pressure during pregnancy, suggesting various impacts depending on exposures and stage of pregnancy. Further research in larger cohorts using personal sensors is necessary to confirm these associations.