Histological changes of human placenta in prolonged pregnancy

الملخص EN

Background : Prolonged pregnancy has been shown to be significantly related to increased risk of perinatal morbidity and mortality.

Objectives : This study aims to determine whether placentas of prolonged pregnancies have developed histological changes compared to those of term gestation and to identify these changes, if any.

It also aims to test whether such changes might begin before 42 weeks of gestation and to evaluate the impact of placental histological changes in prolonged pregnancies on the perinatal outcomes.

Setting : Al-Batool Teaching hospital in Mosul city in Northern Iraq, and Laboratory of Postgraduate Studies at the Department of Anatomy, Histology and Embryology in Mosul College of Medicine.

Methods : This study examined placentas obtained from 220 non-hypertensive, non-diabetic, non- smoker, Rh positive singleton pregnant women who delivered in the hospital over a period of 2 months extending from Aug 1st.

-Sep 30th 2005.

These women were classified into three groups : Group 1 ; includes women who delivered between 38-41 weeks of gestation (n = 100), Group 2 ; includes those delivered between 41-42 weeks (n = 60) and group 3 ; includes women delivered beyond 42 weeks (n = 60).

Results : Sections of group 2 and 3 placental disks showed various histological changes with different frequencies compared with those of group 1.

These changes included hypovascular chorionic villi, syncytial knotting, villous stromal fibrosis, cytotrophoblastic hyperplasia, paucity of vasculosyncytial membranes, thickening of the trophoblastic basement membranes, chorionamnionitis, deciduitis, calcifications, in addition to fibromuscular sclerosis and obliterative endarteritis of the fetal stem arteries.

Adverse perinatal outcomes were more frequent in group 2 and 3 compared with group 1.

A dependent association was identified between adverse perinatal outcomes and several placental histological changes including cytotrophoblastic hyperplasia (p < 0.05), thickening of the trophoblastic basement membrane (p < 0.01), paucity of the vasculosyncytial membranes (VSMs) (p < 0.01), fibromuscular sclerosis (p < 0.05), and obliterative endarteritis of the fetal stem arteries (p < 0.05).

Conclusion : A significant proportion of prolonged pregnancy placentas has developed various histological changes in different proportions compared with those delivered at term with a clear impact on perinatal outcomes.