Clinical and pathogenetic features of early- and late-onset pre-eclampsia. BACKGROUND: PE is present in ∼2-8% of all pregnant women worldwide. Placental bed disorders at early and late PE have been not carried out yet. However, these studies help to explore details of the pathogenesis of PE, and to optimize the prognosis and obstetric management. OBJECTIVE: To identify clinical and morphological differences between early- and late-onset PE based on a comprehensive observation of pregnant women with regard to morphological and immunohistochemical characteristics of the placental bed. MATERIALS AND METHODS: One hundred fifty patients aged 18-43 years old delivered by cesarean section due to severe PE. The samples of placental bed tissue were studied by morphological and immunohistochemical methods. RESULTS: The violation of invasion trophoblast, remodeling of spiral arteries were expressed in early onset PE; the degree of compensation of chronic hypoxia tissue in the area of the placental site was typical for late PE and was absent of an early onset PE. CONCLUSION: Our studies confirm the need for separation of early- and late-onset PE, being justified in terms of different pathogenetic mechanisms of formation, and therefore the possibility of therapeutic effects, duration of pregnancy prolongation, forecasting, search early diagnostic markers of the disease, and personalized approaches.