Morphological and histological variations of human placenta in pregnancies affected with preeclampsia and gestational diabetes – A review

Abstract

The placenta is a transitory organ that is situated between the mother and the foetus. This vital organ which has nutritional, endocrine and immunologic functions so as to maintain pregnancy and promote fetal development. Several factors are related to the proper functioning of the placenta including foetal and maternal blood flow, appropriate nutrients, expression and function of receptors and transporters, and also the morphology of the placenta itself. Gestational hypertension and gestational diabetes are among the most frequent obstetric disorders during pregnancy.  Pregnancies complicated with one or both of these disorders are also associated with adverse consequences for the mother and infant (both acute and long-term). Preeclampsia being one of the toxemias of pregnancy is a condition of increased blood pressure accompanied by proteinuria, edema or both. Various changes like increased syncytial knots, cytotrophoblastic cell proliferation, villous stromal fibrosis and fibrinoid necrosis was observed in placenta from preeclamptic cases. Diabetes mellitus can be defined as a chronic disorder marked by high blood glucose levels and a disruption in fat and protein metabolism. In pregnancies affected by diabetes mellitus also several changes occur like placental size, increased glycogen deposits, increased volume of intervillous space and terminal villi, fibrinoid areas, and glycogen deposits compared to others.All these changes may result in functional changes in this organ thus limiting the wellbeing of the developing foetus. Therefore, this review as a whole gives an overview of morphological changes at macroscopic and histological levels seen in the placenta from gestational diabetes and preeclampsia.