Antifibrinolytic activity in normal pregnancy.

It is found that serum antifibrinolytic activity is inhibitory both to the spontaneous fibrinolytic activity and to the activity of streptokinase-activated plasminogen. The titres of serum antiplasmin activity during gestation, labour, and the puerperium are all of the same order and do not differ from those in non-pregnant women. The marked decrease in the spontaneous fibrinolytic activity in late pregnancy and labour is therefore due to an actual reduction in the circulating active lytic enzyme and is not associated with a change in the antifibrinolytic activity.