The influence of labor and placental separation on hemostasis in term pregnancy

Abstract

We studied the hemostatic effects in 68 term pregnant subjects with normal pregnancy (n = 39), gestational diabetes mellitus (n = 21), pregnancy- induced hypertension (n = 8), during labor, after placental separation, and at 24 hours postpartum. During labor, a hypercoagulable state with enhanced fibrinolysis and platelet activation along with elevated plasminogen activator inhibitor-1 and plasminogen activator inhibitor-2 were seen. In all cases following placental separation, enhanced fibrinolysis persisted with further elevated tissue plasminogen activator antigen and D-dimer levels, increased thrombin generation and platelet activation with decreasing plasminogen activator inhibitor-1 levels. By 24 hours postpartum, thrombin generation (thrombin-antithrombin complex) decreased to a nonpregnant level except for pregnancy induced hypertension, but enhanced prothrombin activation (F1+2) was evident in normal, gestational diabetes mellitus and pregnancy-induced hypertension. Reduced total protein S and antithrombin III activity with normal protein C and elevated fibrinogen levels seen during labor were not affected by delivery. However, although factor VII showed a decreasing trend at 24 hours postpartum it remained elevated above the normal nonpregnant level. At 24 hours postpartum, a hypercoagulable state still persisted in normal, gestational diabetes mellitus and pregnancy-induced hypertension term pregnancy accompanied by enhanced fibrinolysis and elevated plasminogen substrate for fibrinolysis, suggesting a critical dynamic equilibrium between a thrombotic and hemorrhagic state.