Oxidative stress is a prominent pathway for the health effects associated with fine particulate matter (PM_2.5) exposure. Oxidative potential (OP) of PM has been associated to several health endpoints, but its impact on biomarkers of oxidative stress remains insufficient. 300 pregnant women from the SEPAGES cohort (France) carried personal PM_2.5 samplers for a week and OP was measured using ascorbic acid (AA) and dithiothreitol (DTT) assays, and normalized by 1) PM_2.5 mass (OP_m) and 2) sampled air volume (OP_v). A pool of three urine spots collected on the 7th day of PM sampling was analyzed for biomarkers, namely 8-hydroxy-2-deoxyguanosine (8-OHdG), malondialdehyde (MDA) and 8-isoprostaglandin-F2α (8-isoPGF2α). Associations were investigated using adjusted multiple linear regressions. OP effects were additionally investigated by stratifying by median PM_2.5 concentration (14 μg m^-3). In the main models, no association was observed with 8-isoPGF2α, nor MDA. An interquartile range (IQR) increase in OP_m^AA exposure was associated with increased 8-OHdG (percent change: 6.2 %; 95 % CI: 0.2 % to 12.6 %). In the stratified analysis, exposure to OP_m^AA was associated to 8-OHdG for participants exposed to low levels of PM_2.5 (percent change: 11.4 %; 95 % CI: 3.3 % to 20.1 %), but not for those exposed to high levels (percent change: -1.0 %; 95 % CI: -10.6 % to 9.6 %). Associations for OP_m^DTT also followed a similar pattern (p-values for OP_m^AA-PM and OP_m^DTT-PM interaction terms were 0.12 and 0.11, respectively). Overall, our findings suggest that OP_m^AA may be associated with increased DNA oxidative damage. This association was not observed with PM_2.5 mass concentration exposure. The effects of OP_m^AA in 8-OHdG tended to be stronger at lower (below median) vs. higher concentrations of PM_2.5. Further epidemiological, toxicological and aerosol research are needed to further investigate the OP_m^AA effects on 8-OHdG and the potential modifying effect of PM mass concentration on this association.