Prenatal exposure to PM2.5 constituents and newborn leukocyte telomere length in a prospective study: Windows of susceptibility and modification by maternal folic acid supplementation.

Prenatal exposure to fine particulate matter (PM2.5) is related to alterations in newborn telomere length (TL), an indicator of cellular aging. However, the specific effects of PM2.5 constituents and windows of susceptibility are unknown. We aimed to identify the susceptibility windows for prenatal PM2.5 constituents affecting newborn leukocyte TL (LTL) and examine the modifying role of folic acid (FA) supplementation. This study involved 741 maternal-infant dyads from a birth cohort in Wuhan, China. We applied multiple linear regression, distributed lag models, and three multi-pollutant approaches to explore the effects of PM2.5 constituents on newborn LTL. Prenatal PM2.5 constituent exposures were related to shorter newborn LTL. Each 5 µg/m3 increase in organic matter (OM) and nitrate (NO3-), and each 1 µg/m3 increase in black carbon (BC), ammonium (NH4+), and sulfate (SO42-) during the third trimester were related to reductions in LTL of 3.99 % (95 % confidence interval [CI]: -6.36 %, -1.56 %), 6.31 % (95 % CI: -10.67 %, -1.73 %), 6.63 % (95 % CI: -9.87 %, -3.27 %), 3.69 % (95 % CI: -5.99 %, -1.34 %), and 3.00 % (95 % CI: -5.03 %, -0.92 %), respectively. The mixture of PM2.5 constituents was related to shorter newborn LTL, predominantly driven by OM and BC. The detrimental effects of OM, BC, NH4+, and NO3- on newborn LTL were more pronounced in individuals without FA supplementation (all P for interaction < 0.05). Our findings identify the third trimester as a susceptibility window for PM2.5 constituent-induced LTL shortening, with OM and BC as the primary contributors. FA supplementation may help mitigate these effects, highlighting its potential as an intervention strategy.