Ambient air pollution and hypertensive disorders of pregnancy in Rome

Background: Ambient air pollution has been associated with hypertensive disorders of pregnancy (HDP), but few studies rely on assessment of fine-scale variation in air quality, specific subtypes and multi-pollutant exposures. Aim: To study the impact of long-term exposure to individual and mixture of air pollutants on all and specific subtypes of HDP. Methods: We obtained data from 130,470 liveborn singleton pregnacies in Rome during 2014–2019. Spatiotemporal land-use random-forest models at 1 km spatial resolution assigned to the maternal residential addresses were used to estimate the exposure to particulate matter (PM 2.5 and PM 10 ), nitrogen dioxide (NO 2 ), and ozone (O 3 ). Results: For PM 2.5, PM 10 and NO 2 , there was suggestive evidence of increased risk of preeclampsia (PE, n = 442), but no evidence of increased risk for all subtypes of HDP (n = 2297) and gestational hypertension (GH, n = 1901). For instance, an interquartile range of 7.0 μg/m 3 increase in PM 2.5 exposure during the first trimester of pregnancy was associated with an odds ratio (OR) of 1.06 (95% confidence interval: 0.81, 1.39) and 1.04 (0.92, 1.17) after adjustment for NO 2 and the corresponding results for a 15.7 μg/m 3 increase in NO 2 after adjustment for PM 2.5 were 1.11 (0.92, 1.34) for PE and 0.83 (0.76, 0.90) for HDP. Increased risks for HDP and GH were suggested for O 3 in single-pollutant models and for PM after adjustment for NO 2 , but all other associations were stable or attenuated in two-pollutant models. Conclusions: The results of our study suggest that PM 2.5 , PM 10 and NO 2 increases the risk of PE and that these effects are robust to adjustment for O 3 while the increased risks for GH and HDP suggested for O 3 attenuated after adjustment for PM or NO 2 . Additional studies are needed to evaluate the effects of source-specific component of PM on subtypes as well as all types of HDP which would help to target preventive actions.