ObjectiveThe primary objective of this study was to compare the levels of oxidative stress biomarkers between pregnancies with gestational diabetes mellitus (GDM) and normoglycemic pregnancies.Materials and methodsA prospective study was conducted on pregnant women at average risk for GDM. The participants were screened for GDM with glucose challenge test and confirmed by 100 g, 3-h oral glucose tolerance test and categorized into the control (non-GDM) and GDM groups. Maternal blood was collected from all participants at gestational age (GA) 24–28 weeks and early labor and fetal cord blood was collected for measurements of 8 Isoprostane (8Isop) (oxidative stress marker), TNF-α (inflammatory marker) and IL-10 (anti-inflammatory marker) and were followed up for maternal and neonatal outcomes.ResultA total of 62 women, 30 in GDM and 32 in control group, met the inclusion criteria. At 24–28 weeks of gestation, maternal serum 8Isop and TNF-α levels were significantly higher in GDM group (P = 0.032 and P = 0.047), in spite of good glycemic control. At early labor, maternal 8Isop levels were significantly higher in GDM (P = 0.001). The biomarkers in the cord blood as well as maternal and neonatal outcomes in both groups were not significantly different.ConclusionGDM is significantly associated with inflammatory process when compared to normal pregnancy, as indicated by higher oxidative stress and apoptosis markers. However, such levels were not correlated with the pregnancy outcomes. An increase in oxidative stress could not be prevented by good glycemic control. Cord blood biomarker levels in pregnancy with GDM were not changed, suggesting that the placenta could be the barrier for the oxidative stress and cytokines.