Neonatal and maternal fibrinolysis: activation at time of birth.

Utilizing chromogenic synthetic substrate-based methods, determination of the plasma concentration of plasminogen, alpha 2-antiplasmin, alpha 2-macroglobulin, and B beta 15-42-related peptides were made at the time of birth in both newborns and mothers. Plasminogen levels were increased in the maternal group (150 +/- 26%), and markedly decreased in the newborn group (67 +/- 14%). The major inhibitors of fibrinolysis, alpha 2-antiplasmin and alpha 2-macroglobulin, were within normal range in both groups. Determination of B beta 15-42-related peptide showed markedly increased levels in the maternal group above control values (115 +/- 102, normal 29 +/- 12); the newborn group showed values only mildly elevated above control values (39 +/- 21). The results demonstrate increased fibrinolytic activity in both groups, though the degree of activation is significantly higher in the maternal group, as reflected by the higher levels of B beta 15-42-related peptides. Fibrinopeptide A levels confirm an activation of coagulation in both maternal and newborn groups (22 +/- 4 ng/ml and 138 +/- 22 ng/ml, respectively) with a significantly increased level in newborns (2-5 ng/ml normal).