- Preeclampsia, one of the main complications in pregnancy, affects 5-7% of all pregnancies, and is a leading cause of maternal and perinatal mortality. The placenta plays a pivotal role in the etiology of preeclampsia, and particularly, the trophoblast cells of the placenta. It is now believed that preeclampsia is a two stage disease. In the first stage, a defective implantation and placentation, causes a reduction in uteroplacental perfusion and placental ischemia/hypoxia. Placental ischemia may promote the release of a variety of factors to the maternal circulation. In the second stage, these factors initiate a cascade of cellular and molecular events leading to endothelial and vascular dysfunction. The endothelial dysfunction leads to the clinically recognized symptoms of the syndrome, which include hypertension, proteinuria, thrombocytopenia and impaired liver function. Hypertension is mediated by various endothelial and non-endothelial regulatory factors that are altered in preeclampsia. This review aims to summarize the recent knowledge on the implication of the placenta and various angiogenic factors in the pathogenesis of preeclampsia.