Exposure to high levels of PM2.5 from the second trimester onwards was most strongly associated with increased risk of pre-term birth and low birthweight. - GreenMedInfo Summary
Prenatal PMexposure and the risk of adverse births outcomes: Results from Project ELEFANT.
Environ Res. 2020 12 ;191:110232. Epub 2020 Sep 19. PMID: 32961173
Junkai Fang
BACKGROUND: Studies investigating the impact of fine particulate matter (PM) exposure during pregnancy upon adverse birth outcomes have primarily been performed in Western nations with low ambient PMlevels. We examined associations between high levels of PMexposure during pregnancy and risk of adverse birth outcomes by timing and level of exposure in a Chinese population.
METHODS: We analysed data from 10,738 live births within the Project ELEFANT study based in Tianjin, China. Personal mean daily PMexposures were estimated using data from 25 local monitoring sites across the city, used to compute the days exceeding 50, 100, 150, 200 and 250 μg/m. Relative risk of pre-term birth (<37 weeks) and low birthweight (<2500 g) were estimated by generalized additive distributed lag models, adjusted for maternal age, sex, region, paternal smoking, parity, maternal occupation, season, temperature and dew point.
RESULTS: A dose-response was exhibited for PMexposure and relative risk (RR) of adverse birth outcomes, with exposure in the second and third trimesters of pregnancy associated with greatest risk of adverse birth outcomes. The RRs of pre-term birth with exposures of>50,>150 and > 250 μg/mPMin the third trimester were 1.09 (95%CI: 1.03-1.16), 1.30 (1.09-1.54) and 2.73 (2.03-3.66) respectively. For low birthweight, exposures of>50,>150 and > 250 μg/mPMin the third trimester were associated with RRs of 0.99 (0.88-1.11), 1.37 (1.04-1.81) and 3.03 (1.75-5.23) respectively.
CONCLUSIONS: Exposure to high levels of PMfrom the second trimester onwards was most strongly associated with increased risk of pre-term birth and low birthweight, with a dose-response relationship. Our data demonstrates the need to account for both level and timing of exposure in analysis of PM-associated birth outcomes.