Qin Li1,2,3, Yuan-Yuan Wang2,4, Yuming Guo5, Hong Zhou1,2, Xiaobin Wang6,7, Qiao-Mei Wang8, Hai-Ping Shen8, Yi-Ping Zhang8, Dong-Hai Yan8, Shanshan Li5, Gongbo Chen5, Lizi Lin1, Yuan He4, Ying Yang4, Zuo-Qi Peng4, Hai-Jun Wang1,2, Xu Ma2,4. 1. Department of Maternal and Child Health, School of Public Health, Peking University, Beijing, China. 2. Environmental and Spatial Epidemiology Research Center, National Human Genetic Resources Center, Beijing, China. 3. Reproductive Medical Centre, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, China. 4. National Research Institute for Family Planning, Beijing, China. 5. Department of Epidemiology and Preventive Medicine, School of Public Health and Preventive Medicine, Monash University, Melbourne, Victoria, Australia. 6. Center on the Early Life Origins of Disease, Department of Population, Family and Reproductive Health, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, USA. 7. Department of Pediatrics, School of Medicine, Johns Hopkins University, Baltimore, Maryland, USA. 8. Department of Maternal and Child Health, National Health Commission of the People's Republic of China, Beijing, China.
Abstract
BACKGROUND: Potential modification of the association between maternal particulate matter (PM) exposure and preterm delivery (PTD) by folic acid (FA) supplementation has not been studied. OBJECTIVE: We examined whether FA supplementation could reduce the risk of PTD associated with maternal exposure to PM in ambient air during pregnancy. METHOD: In a cohort study covering 30 of the 31 provinces of mainland China in 2014, 1,229,556 primiparas of Han ethnicity were followed until labor. We collected information on their FA supplementation and pregnancy outcomes and estimated each participant's exposure to PM with diameters of ≤10μm (PM10), 2.5μm (PM2.5), and 1μm (PM1) using satellite remote-sensing based models. Cox proportional hazard regression models were used to examine interactions between FA supplementation and PM exposures, after controlling for individual characteristics. RESULTS: Participants who initiated FA ≥3 months prior to pregnancy (38.1%) had a 23% [hazard ratio (HR)=0.77 (95% CI: 0.76, 0.78)] lower risk of PTD than women who did not use preconception FA. Participants with PM concentrations in the highest quartile had a higher risk of PTD [HR=1.29 (95% CI: 1.26, 1.32) for PM1, 1.52 (95% CI: 1.46, 1.58) for PM2.5, and 1.22 (95% CI: 1.17, 1.27) for PM10] than those with exposures in the lowest PM quartiles. Estimated associations with a 10-μg/m3 increase in PM1 and PM2.5 were significantly lower among women who initiated FA ≥3 months prior to pregnancy [HR=1.09 (95% CI: 1.08, 1.10) for both exposures] than among women who did not use preconception FA [HR=1.12 (95% CI: 1.11, 1.13) for both exposures; pinteraction<0.001]. The corresponding association was also significantly lower for a 10-μg/m3 increase in PM10 [HR=1.03 (95% CI: 1.02, 1.03) for FA ≥3 months before pregnancy vs. 1.04 (95% CI: 1.03, 1.04) for no preconception FA; pinteraction<0.001]. CONCLUSION: Our findings require confirmation in other populations, but they suggest that initiating FA supplementation ≥3 months prior to pregnancy may lessen the risk of PTD associated with PM exposure during pregnancy among primiparas of Han ethnicity. https://doi.org/10.1289/EHP6386.
BACKGROUND: Potential modification of the association between maternal particulate matter (PM) exposure and preterm delivery (PTD) by folic acid (FA) supplementation has not been studied. OBJECTIVE: We examined whether FA supplementation could reduce the risk of PTD associated with maternal exposure to PM in ambient air during pregnancy. METHOD: In a cohort study covering 30 of the 31 provinces of mainland China in 2014, 1,229,556 primiparas of Han ethnicity were followed until labor. We collected information on their FA supplementation and pregnancy outcomes and estimated each participant's exposure to PM with diameters of ≤10μm (PM10), 2.5μm (PM2.5), and 1μm (PM1) using satellite remote-sensing based models. Cox proportional hazard regression models were used to examine interactions between FA supplementation and PM exposures, after controlling for individual characteristics. RESULTS:Participants who initiated FA ≥3 months prior to pregnancy (38.1%) had a 23% [hazard ratio (HR)=0.77 (95% CI: 0.76, 0.78)] lower risk of PTD than women who did not use preconception FA. Participants with PM concentrations in the highest quartile had a higher risk of PTD [HR=1.29 (95% CI: 1.26, 1.32) for PM1, 1.52 (95% CI: 1.46, 1.58) for PM2.5, and 1.22 (95% CI: 1.17, 1.27) for PM10] than those with exposures in the lowest PM quartiles. Estimated associations with a 10-μg/m3 increase in PM1 and PM2.5 were significantly lower among women who initiated FA ≥3 months prior to pregnancy [HR=1.09 (95% CI: 1.08, 1.10) for both exposures] than among women who did not use preconception FA [HR=1.12 (95% CI: 1.11, 1.13) for both exposures; pinteraction<0.001]. The corresponding association was also significantly lower for a 10-μg/m3 increase in PM10 [HR=1.03 (95% CI: 1.02, 1.03) for FA ≥3 months before pregnancy vs. 1.04 (95% CI: 1.03, 1.04) for no preconception FA; pinteraction<0.001]. CONCLUSION: Our findings require confirmation in other populations, but they suggest that initiating FA supplementation ≥3 months prior to pregnancy may lessen the risk of PTD associated with PM exposure during pregnancy among primiparas of Han ethnicity. https://doi.org/10.1289/EHP6386.
Authors: Nasser Laouali; Tarik Benmarhnia; Bruce P Lanphear; Jennifer Weuve; Michael Mascari; Marie-Christine Boutron-Ruault; Youssef Oulhote Journal: Environ Epidemiol Date: 2022-01-25