Alteration of placental haemostatic mechanisms in idiopathic intrauterine growth restriction

Intrauterine growth restriction is a complication of pregnancy with a high probability of perinatal morbidity and mortality. It appears to be caused by abnormal development of placental vasculature. Haemostatic processes are important for the development of the placenta, and an imbalance between procoagulant and anticoagulant factors has been associated with risk of intrauterine growth restriction. Objective: To evaluate coagulation abnormalities in placenta of pregnancies complicated with idiopathic intrauterine growth restriction. Materials and methods: Five placentas from pregnancies with idiopathic intrauterine growth restriction were compared to 19 controls. We performed gross and histological examination of the placenta. Analysis was made of both mRNA expression by real-time PCR and protein by ELISA of tissue factor and thrombomodulin in placental tissue. Results: Results based on histological evaluation were consistent with an increased prothrombotic state in placentas from pregnancies with idiopathic intrauterine growth restriction, and thrombosis of chorionic vessels was the most important finding. The study showed an increased expression of tissue factor protein (p=0.0411) and an increase in the ratio of tissue factor/thrombomodulin mRNA (p=0.0411) and protein (p=0.0215) in placentas from pregnancies with idiopathic intrauterine growth restriction. There were no statistically significant differences neither between cases and controls in the mRNA levels of tissue factor or thrombomodulin nor at the protein level of thrombomodulin. Conclusion: Evidence of alteration of local haemostatic mechanisms at the level of the placenta, including abnormal expression of tissue factor and tissue factor/thrombomodulin ratio, in pregnancies that occur with idiopathic intrauterine growth restriction is presented.