Prenatal exposure to polycyclic aromatic hydrocarbons and heating-season air pollution: associations with birth outcomes in a coal-reliant city

Objectives As air pollutants and polycyclic aromatic hydrocarbons (PAHs) can enter the human body through multiple routes, prenatal exposure may compromise neonatal development. This study characterizes heating-season air pollution exposure and PAH detection among pregnant women and neonates in Urumqi, a coal-reliant city in northwestern China with severe winter air pollution, and evaluates its association with neonatal birth outcomes. Methods Between June 2019 and January 2020, we enrolled 279 mother-infant pairs in Urumqi. Participants were stratified into long and short heating-season exposure groups based on the duration of gestational overlap with the municipal heating period. Sixteen PAHs were analyzed in paired maternal and umbilical cord plasma samples using gas chromatography–mass spectrometry (GC–MS), and detection rates were calculated. We compared neonatal anthropometric outcomes, maternal lifestyle factors, and ambient air pollution levels between groups, and examined correlations between air pollutants and neonatal outcomes. Multivariable linear regression models were established to examine the associations between heating-season exposure (LHPEG vs. SHPEG) and neonatal outcomes after adjusting for potential confounders. In a sensitivity analysis, DGOHP was treated as a continuous variable. Results The detection rates of the 16 PAHs ranged from 66.02 to 91.08% in maternal plasma and from 47.68 to 77.64% in cord plasma. Neonates in the long heating-season exposure group (LHPEG) had significantly lower body length, Ponderal Index than those in the short-exposure group (SHPEG) ( p = 0.002 for body length). No significant difference was observed for birth weight ( p = 0.132). In the sensitivity analysis, each 1-day increase in DGOHP was associated with a 0.011 cm decrease in body length ( p = 0.004). Higher gestational exposure to PM 2.5 and PM 10 was also associated with reduced body length. Conclusion Prolonged heating-season air pollution exposure in Urumqi is associated with reduced neonatal body length. PAHs were widely detected in maternal and cord plasma, indicating widespread exposure. These findings support the need for public health strategies to reduce air pollution exposure among pregnant women in coal-reliant regions with long heating seasons.