Prenatal air pollution exposure and placental biomarkers of oxidative stress and ageing: results from the BiSC cohort.

Prenatal air pollution exposure has been associated with impaired fetal growth. However, the underlying biological mechanisms, potentially involving the placenta, remain poorly understood. This study aimed to investigate the effects of maternal air pollution exposure on placental biomarkers of oxidative stress and cellular ageing, and to determine whether these biomarkers contribute to the association between air pollution exposure and birth weight. The study included 499 participants from the Barcelona Life Study Cohort (BiSC), recruited between October 2018 and April 2021. Maternal exposure to nitrogen dioxide (NO2), black carbon, and particulate matter ≤2.5 μm (PM2.5) during pregnancy was estimated using hybrid Land Use Regression (LUR)-dispersion models. Placental relative mitochondrial DNA content (mtDNAcn) and telomere length (TL) were measured by qPCR, and associations between exposure and placental biomarkers were estimated using linear mixed-effects regression models adjusted for covariates. Increasing levels of NO2 and PM2.5 during the 1st and 3rd trimesters and across the entire pregnancy, as well as black carbon during the 3rd trimester, were significantly associated with an increase in placental mtDNAcn. No significant associations were observed between prenatal air pollution exposure and placental TL, nor between either placental biomarker and birth weight. In conclusion, prenatal air pollution exposure was associated with differences in placental mtDNAcn but not TL, and neither biomarker was significantly associated with birth weight.