Fibrinolysis in normal pregnancy.

It is well known that a low level of circulating fibrinogen may be associated with bleeding in a variety of obstetric complications, as, for example, accidental haemorrhage. The actual cause, however, ofthe depletion offibrinogen in these conditions is debatable (Moore, 1955), but one feature of such states is the frequent presence of a circulating proteolytic agent which is capable of destroying fibrin. It is possible that this agent is responsible for the bleeding, though attempts to demonstrate it have not always been successful. One explanation of the failure to detect lysis is suggested by the work of Feamley, Revill, and Tweed (1952), who showed that plasma fibriuolytic activity is thermolabile. This activity is quickly destroyed at room temperature, but can be preserved by keeping the plasma at ice temperature. Such a precaution has been adopted in the present work, which is concerned with the behaviour of plasma fibrinolytic activity in normal pregnancy, labour, and the puerperium.