Relationship between environmental pollution exposure and preterm birth: Mediating role of placental oxidative stress

Environmental pollution is a known risk factor for preterm birth, with oxidative stress in the placenta potentially mediating this relationship.This study aimed to explore the link between maternal exposure to environmental pollution and preterm birth, with placental oxidative stress as a potential mediator.A hospital-based analytical cross-sectional study was conducted at Babylon Teaching Hospital, Iraq, from November 2024 to March 2025.The study included 240 postpartum women, divided into preterm and postpartum groups.Environmental exposure was measured using air quality data, while placental oxidative stress was evaluated with biomarkers (malondialdehyde and superoxide dismutase).The data were analyzed using descriptive statistics, chi-square tests, t-tests, logistic regression and mediation analysis using the PROCESS macro.Preterm birth was associated with higher levels of environmental pollutants such as PM2.5 (42.6 9.1 g/m vs. 31.4 7.6 g/m), NO (30.8 6.4 ppb vs. 23.2 5.9 ppb), and SO (18.5 4.8 ppb vs. 13.7 3.9 ppb) compared to term births.Placental MDA levels were higher (5.61 1.25 vs. 3.12 0.96 nmol/mg), and SOD activity was lower (9.18 1.96 vs. 12.74 2.41 U/mg protein) in the preterm group.Mediation analysis revealed that placental oxidative stress partially mediated the relationship between PM2.5 exposure and preterm birth (36.8% mediation).Maternal exposure to environmental pollutants is associated with an increased risk of preterm delivery, with oxidative stress playing a mediating role.Interventions aimed at reducing exposure to pollution and promoting maternal health can mitigate these risks.