Morphometric and Histological Changes of the Placenta in Hypertensive Disorders of Pregnancy

The placenta is the discoid foeto-maternal organ which maintains pregnancy and promotes normal foetal development. The human placenta is a hemo-chorial placenta where the maternal blood directly comes in contact with the foetal trophoblast. Functions of placenta include gas exchange, metabolic transfer, hormone secretion and foetal protection. Hypertension is a common complication of pregnancy which significantly contributes to the perinatal and maternal mortality and morbidity. 5 % to 8% of all maternal deaths are due to hypertension during pregnancy. Complications of hypertensive disorders of pregnancy are reflected in the placenta in a significant way both macroscopically and microscopically. Study of placenta is useful in understanding the pathophysiology of the placenta. Previous studies on preeclamptic placentae revealed a significant decrease in morphological parameters like weight, diameter, thickness, surface area, volume, and cotyledon number. Various histological changes like increased syncytial knots, cytotrophoblastic proliferation, fibrinoid necrosis, stromal fibrosis, and calcification were also noted in the placenta from preeclamptic cases. The changes in placental structure and function can have significant implications for the well-being and development of the fetus. This review gives an overview of both morphological and histological changes of placentae in hypertensive disorders of pregnancy.