Telomere length in newborns is associated with exposure to low levels of air pollution during pregnancy

Telomere length (TL) is a biomarker of biological aging that may be affected by prenatal exposure to airpollution. The aim of this study was to assess the association between prenatal exposure to air pollution and TL inmaternal blood cells (leukocytes), placenta and umbilical cord blood cells, sampled immediately after birth in296 Danish mother-child pairs from a birth cohort. Exposure data was obtained using the high-resolution andspatial–temporal air pollution modeling system DEHM-UBM-AirGIS for PM2.5, PM10, SO2, NH4+, black carbon(BC), organic carbon (OC), CO, O3, NO2, and NOx at residential and occupational addresses of the participatingwomen for the full duration of the pregnancy. The association between prenatal exposure to air pollutants and TLwas investigated using distributed lag models. There were significant and positive associations between TL inumbilical cord blood cells and prenatal exposure to BC, OC, NO2, NOx, CO, and O3 during the second trimester.TL in umbilical cord blood was significantly and inversely associated with prenatal exposure to PM2.5, BC, OC,SO2, NH4+, CO and NO2 during the third trimester. There were similar inverse associations between TL fromumbilical cord blood cells and air pollution exposure at the residential and occupational addresses. There wereweaker or no associations between air pollution exposure and TL in placenta tissue and maternal blood cells. Inconclusion, both the second and third trimesters of pregnancy are shown to be sensitive windows of exposure toair pollution affecting fetal TL