Industrial emissions and risks of preterm and small-for-gestational-age birth: A population-based cohort study in Quebec, Canada

Abstract

Background: Ambient air pollution has been linked to adverse birth outcomes, but the role of industrial emissions remains understudied. We examined the association between maternal exposure to industrial air pollutants during pregnancy and the risk of preterm birth (PTB) and small-for-gestational-age (SGA) birth. Methods: We conducted a retrospective cohort study of 1,199,516 singleton live births in Quebec, Canada, from 2002 to 2016. Exposure to PM2.5, NO2, and SO2 emitted by industries within 7.5 km of the maternal residence was estimated using an indicator combining residential proximity, emissions, and wind data. Logistic regression models were used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for PTB and SGA comparing exposed to unexposed individuals. We assessed the modifying effects of maternal comorbidities using subgroup analyses. Results: The cohort comprised 71,699 PTB and 105,894 SGA cases. Compared with unexposed participants, exposure to industrial air pollutants during pregnancy increased the risk of extreme and very PTB and SGA. For extreme PTB, adjusted ORs (95% CI) comparing exposed with unexposed were 1.08 (1.00, 1.17) for PM2.5, 1.11 (1.03, 1.19) for NO2, and 1.05 (0.98, 1.12) for SO2. For SGA, the corresponding values were 1.03 (1.02, 1.05) for PM2.5, 1.03 (1.02, 1.04) for NO2, and 1.05 (1.04, 1.06) for SO2. Exposure to NO2 was associated with a higher risk of extreme and very PTB among mothers with preeclampsia (OR: 1.26; 95% CI: 1.12, 1.42) compared with no preeclampsia (OR:1.07; 95% CI: 1.01, 1.12). Conclusion: Exposure to industrial air emissions during pregnancy may increase the risk of extreme and very PTB and SGA, especially among women with preeclampsia.