Impact of air pollution exposure during various periods of pregnancy on term birth weight: a large-sample, retrospective population-based cohort study

Abstract

Previous studies have suggested that maternal exposure to air pollution might affect term birth weight. However, the conclusions are controversial. Birth data of all term newborns born in Xi’an city of Shaanxi, China, from 2015 to 2018 and whose mother lived in Xi’an during pregnancy were selected form the Birth Registry Database. And the daily air quality data of Xi’an city was collected from Chinese Air Quality Online Monitoring and Analysis Platform. Generalized additive models (GAM) and 2-level binary logistic regression models were used to estimate the effects of air pollution exposure on term birth weight, the risk term low birth weight (TLBW), and macrosomia. Finally, 321521 term newborns were selected, including 4369(1.36%) TLBW infants and 24,960 (7.76%) macrosomia. The average pollution levels of PM2.5, PM10, and NO2 in Xi’an city from 2015 to 2018 were higher than national limits. During the whole pregnancy, maternal exposure to PM2.5, PM10, SO2, and CO all significantly reduced the term birth weight and increased the risk of TLBW. However, NO2 and O3 exposure have significantly increased the term birth weight, and O3 even increased the risk of macrosomia significantly. Those effects were also observed in the first and second trimesters of pregnancy. But during the third trimester, high level of air quality index (AQI) and maternal exposure to PM2.5, PM10, SO2, NO2, and CO increased the term birth weight and the risk of macrosomia, while O3 exposure was contrary to this effect. The findings suggested that prenatal exposure to air pollution might cause adverse impacts on term birth weight, and the effects varied with trimesters and pollutants, which provides further pieces of evidence for the adverse effects of air pollution exposure in heavy polluted-area on term birth weight.

Association of Seasonal Ambient Air Pollution With a Risk of Adverse Perinatal Outcomes in Full-term Pregnancies: A Retrospective Cohort Study in Wenzhou, China

“…The majority of studies reported positive or null associations between air pollution and LBW in the 3rd trimester (Bosetti et al 2010.We observed that maternal exposures to air pollution (PM 2.5 , PM 10 , SO 2, and NO 2 ) in the 3rd pregnancy were negatively related to TLBW in single pollutant models, which were only consistent with one study (Shang et al 2021).…”

“…The associations between PM 2.5 , PM 10 , SO 2, and NO 2 exposure and TLBW/ macrosomia were stronger in women who conceived in the warm season compared with those who conceived in the cold season. A retrospective cohort study based on birth records in Guangdong province reported that O 3 exposure was associated with LBW for the babies conceived in cold season (Wang et al 2021). Wang et al found that the associations between air pollution and SGA varied by season of conception.…”

“…These results were similar to several previous studies. One study of Shaanxi Province in China reported that maternal exposure to PM 2.5 , PM 10 , SO 2, and NO 2 increased the term birth weight and increased the risk of macrosomia in the 3rd trimester (Shang et al 2021). Another nationwide study in China showed that every 10 μg/m 3 increase of PM 2.5 concentration, the macrosomia risk increased by 3.3% over the 3rd trimester (Chen et al 2020).…”

“…Several epidemiological studies evaluated the effects of air pollution on the risk of macrosomia, with the inconsistent ndings over different trimesters. Shang et al (Shang et al 2021) reported that maternal exposure to PM 2.5 , PM 10 , SO 2 , and NO 2 in the 3rd trimester increased the term birth weight and increased the risk of macrosomia, but showed contrary effects during the 1st and 2nd trimesters, and the entire pregnancy. Another nationwide study in China found that maternal exposure to PM 2.5 increased the risk of macrosomia over the 1st, 2nd, 3rd trimesters and the entire pregnancy (Chen et al 2020).…”

“…Season of conception is an important factor affecting the association between air pollution and birth weight. Most studies only adjusted the season as a confounding factor in the model (Consortium on et al 2019, Li et al 2019b, Shang et al 2021, instead of treating it as a major research factor. It has been proposed that season of conception involved in air pollutant concentration and composition could explain part of the link between intrauterine fetal growth and risk of adverse perinatal outcomes, and the biological responsiveness of the human body to air pollution might vary with seasons (Kim et al 2017).…”