Critical windows for maternal fine particulate matter exposure and adverse birth outcomes: The Shanghai birth cohort study

Abstract Background Prenatal exposure to ambient levels of air pollution has been reported to adversely affect birth outcomes, yet few studies have investigated refined susceptible windows for adverse birth outcomes. Objectives The study aimed at estimating associations between maternal exposure to ambient fine particulate matter (PM2.5; particles with an aerodynamic diameter ≤ 2.5 μm) and birth outcomes, including birth weight, low birth weight (LBW) and preterm birth (PTB), and identify specific susceptible windows. Methods A total of 3692 singleton live births were enrolled between 2013 and 2016 in Shanghai Birth Cohort, China. Based on mothers’ residential addresses, weekly mean concentrations of PM2.5 over gestation were estimated based on an incorporated evaluating approach combining satellite-based estimates and ground-level measurements. Distributed lag non-liner models (DLNMs) were fitted by incorporating with multiple liner models and Cox proportional hazard models to evaluate weekly-as well as trimester-exposure-lag-response associations between average PM2.5 level and birth weight, LBW and PTB, and to identify critical windows. Results In this study, gestational exposure to PM2.5 was associated with adverse birth outcomes in infants, and critical windows were identified as 31st–34th gestational weeks for reduced birth weight, 38th–42 nd weeks for LBW and 27th–30th weeks for PTB, respectively. Trimester-specific associations were found for all birth outcomes during the third trimester. Conclusions Ambient PM2.5 exposure exhibited adverse impacts on multiple outcomes including reduced birth weight, LBW and PTB in the late pregnancy. The study provides further evidence supporting harmful effects of maternal PM2.5 exposure on birth outcomes and identifying critical windows.