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The pathophysiology of preeclampsia (PE), a disorder occurring in 5% of all pregnancies, remains largely unknown, but early placental hypoxia and oxidative stress are known to be involved in the mechanism of the syndrome. Maternal plasma and placental tissue samples were collected from PE, intrauterine growth restriction (IUGR), and normotensive pregnant patients. The immunohistochemical expression of vascular endothelial growth factor (VEGF), malondialdehyde (MDA) production and the activity of antioxidant enzymes (superoxide dismutase, catalase and glutathione peroxidase GSH-Px) were determined in the placental tissue. F2-isoprostane concentration and the ferric reducing ability of plasma (FRAP) were determined in maternal plasma. We found that the PE and IUGR groups showed a higher expression of VEGF in the muscular layer of fetal chorionic vessels. In addition, increased plasma F2 isoprostane levels and a significant reduction of FRAP in the plasma of PE women, as well as a lower activity of SOD in PE placentas and a higher activity of GSH-Px in IUGR placentas were found. Additionally, lower PlGF and higher sFlt1 levels were observed in the maternal plasma of PE and IUGR than control. We concluded that in a hypoxic environment, the placenta expresses VEGF in the muscular layer of fetal vessels. The development of PE could be related to the increased expression of VEGF, with decreased placental SOD activity and a decrease of both plasma F2-isoprostane and FRAP levels. In turn, the development of IUGR could be related to the association of decreased plasma FRAP levels and increased placental GSH-Px activity.