Association between Maternal Exposure to Ambient Air Pollution and the Risk of Preterm Birth: A Birth Cohort Study in Chongqing, China, 2015–2020

Abstract

Recent study results on the association between maternal exposure to ambient air pollution with preterm birth have been inconsistent. The sensitive window of exposure and influence level of air pollutants varied greatly. We aimed to explore the association between maternal exposure to ambient air pollutants and the risk of preterm birth, and to estimate the sensitive exposure time window. A total of 572,116 mother–newborn pairs, daily concentrations of air pollutants from nearest monitoring stations were used to estimate exposures for each participant during 2015–2020 in Chongqing, China. We applied a generalized additive model and estimated RRs and 95% CIs for preterm birth in each trimester and the entire pregnancy period. In the single-pollutant model, we observed that each 10 μg/m3 increase in PM2.5 had a statistically significant effect on the third trimester and entire pregnancy, with RR = 1.036 (95% CI: 1.021, 1.051) and RR = 1.101 (95% CI: 1.075, 1.128), respectively. Similarly, for each 10 μg/m3 increase in PM10, there were 2.7% (RR = 1.027, 95% CI: 1.016, 1.038) increase for PTB on the third trimester, and 3.8% (RR = 1.038, 95% CI: 1.020, 1.057) increase during the whole pregnancy. We found that for each 10 mg/m3 CO increases, the relative risk of PTB increased on the first trimester (RR = 1.081, 95% CI: 1.007, 1.162), second trimester (RR = 1.116, 95% CI: 1.035, 1.204), third trimester (RR = 1.167, 95% CI: 1.090, 1.250) and whole pregnancy (RR = 1.098, 95% CI: 1.011, 1.192). No statistically significant RR was found for SO2 and NO2 on each trimester of pregnancy. Our study indicates that maternal exposure to high levels of PM2.5 and PM10 during pregnancy may increase the risk for preterm birth, especially for women at the late stage of pregnancy. Statistically increased risks of preterm birth were associated with CO exposure during each trimester and entire pregnancy. Reducing exposure to ambient air pollutants for pregnant women is clearly necessary to improve the health of infants.

Associations between maternal exposure to ambient air pollution and very low birth weight: A birth cohort study in Chongqing, China

“…Research data for this study was gathered from a large retrospective cohort of live births from 2015 to 2020, in Chongqing, China, which was consistent with our previously published paper ( 13 ), all birth data were extracted from the birth certificate system database for Chongqing. This database contains maternal age, maternal residence address, date of birth, birth weight, gestational age, etc.…”

“…Air pollution exposure assessment was carried out using the same method as our published paper ( 13 ) mentioned above. Based on the detailed residence address of every researched pregnant woman and the location of air monitoring stations, we calculated the distance between each maternal residence and the monitoring sites using ArcGIS (version 10.2).…”

“…To evaluate the association between ambient air pollutant exposure and the risk of VLBW in each exposure period, we performed a Generalized Additive Model (GAM), also consistent with our previously published paper ( 13 ). The effects were examined for both single-pollutant and multiple-pollutant models.…”

The Temporal Relationship Between the Coronavirus Disease 2019 (COVID-19) Pandemic and Preterm Birth

“…[8][9][10][11] Conversely, the pandemic, particularly during the most extensive lockdowns, has resulted in less pollution and other adverse environmental factors that are considered to be potentially protective of preterm birth. [12][13][14] Nevertheless, the epidemiologic studies that have evaluated the relationship between the COVID-19 pandemic and preterm birth have had inconsistent results. Some have shown no change, some have shown a decreased risk, and some have shown an increased risk of preterm birth after the onset of the pandemic.…”