Background/Aims: To evaluate the incidence of placental abnormalities, cord plasma erythropoietin (EPO) levels and nucleated red blood cell (NRBC) counts, maternal and cord plasma malondialdehyde (MDA) and vascular endothelial growth factor (VEGF) levels in women with gestational diabetes mellitus (GDM) and nondiabetic controls. Methods: Twenty-two women with GDM, diagnosed according to the current criteria of the American Diabetes Association, were compared with 22 controls. Maternal and cord blood and placental samples were obtained from all pregnant women. Cord plasma EPO levels and NRBC counts, maternal and cord plasma MDA and VEGF levels were determined. Placental tissues were examined histologically. Results: Maternal and cord plasma levels of MDA and cord plasma EPO levels and NRBC counts were significantly higher in GDM pregnancies (p < 0.01). The presence of villous immaturity, chorangiosis and ischemia were significantly increased in the placentas of women with GDM ( p < 0.05). The maternal and cord plasma levels of MDA increased (p = 0.007 and p = 0.001, respectively), whereas VEGF decreased (p = 0.046 and p = 0.001, respectively) with the presence of villous immaturity. Conclusion: The complex process of villous development and maturity might be influenced by the maternal and fetal oxidative and angiogenetic milieu. The placenta that shows abnormalities in angiogenesis and maturation may lead to fetal hypoxia and compromise. Copyright (c) 2008 S. Karger AG, Basel.