The relationship between the onset of labor mechanisms and the hemostatic system

Abstract

The relationship between onset of labor and the hemostatic system was evaluated in 38 pregnant women. The hemostatic system consists of blood coagulation, kinin–kallikrein system, the fibrinolytic system, and platelet function. The most prominent changes take place in the kinin–kallikrein system. After the onset of labor, prekallikrein decreases rapidly which may trigger changes in blood coagulation and the fibrinolytic system. Platelet hemostatic capacity (PHC) was also measured using the PFA-100 (platelet function analyzer) system. Closure times (CT) were shorter during pregnancy, compared to non-pregnant controls, suggesting an increase in PHC. Platelet aggregation by ADP at the end of pregnancy was decreased at the onset of labor. At the same time a slight increase in FDP (fibrin degeneration product) was also seen. While FDP increased, platelet aggregation decreased, which seems to suggest FDP inhibits platelet aggregation. In this manner, these three systems(kinin–kallikrein system, blood coagulation, and fibrinolytic system) and platelet aggregation are closely interrelated, possibly affecting uterine contractility during pregnancy and the onset of labor.