Detection of human fetal fibrinogen in umbilical cord plasma by parallel assays of immunoreactive and thrombin-clottable protein.

Putative fetal fibrinogen was detected in normal human umbilical cord plasma by parallel assays of immunoreactive and thrombin-clottable protein. The 'excess' of immunoassayable fibrinogen was not due to products of proteolysis and the apparent 'insensitivity' to thrombin was reflected in delayed fibrin polymerization. Fetal fibrinogen was partially separable from the adult protein by two-dimensional immunoelectrophoresis.