EFFECTS OF LABOR AND DELIVERY ON FIBRINOLYSIS

Because timing of sampling is crucial in an investigation of the effec ts of labor and delivery on fibrinolysis we e conducted a study of fib rinolytic markers in plasma of 10 healthy multiparous women in whom la bor was induced, which allowed standardization of sampling times in re lation to the course of labor and delivery. Blood samples were taken 5 min before-the start of oxytocin infusion, at full cervical dilatatio n, and within 5 min after delivery of the placenta. A sample of mixed free flowing cord blood was obtained after delivery with the placenta in situ. Variables determined were tissue-type plasminogen-activator ( t-PA) and the plasminogen activator inhibitors type 1 (PAI-1) and type 2 (PAI-2). The only significant change between the beginning of the i nduction of labor and the end of the first stage of labor was a rise i n t-PA antigen (P = 0.01). All variables, except PAI-2 antigen, change d significantly after delivery of the placenta: t-PA antigen and activ ity showed a rise (P < 0.05), accompanied by a fall in PAI-I antigen a nd activity (P < 0.01). T-PA activity in cord plasma was higher(P < 0. 01) in comparison with maternal plasma concentrations at the end of th e first stage of labor, t-PA antigen levels were similar, and PAI-I an tigen and activity and PAI-2 antigen were lower in cord plasma (P < 0. 001). Our study shows that activation of the maternal fibrinolytic sys tem can already be detected during labor, with a marked further increa se in fibrinolyic potential after placental separation.