Measurement of euglobulin fibrinolysis time in women with retarded fetal development. The effect of the clamping and step tests on plasminogen activator activity.

The effects of two experimental stimuli, clamping of the cubital vein and exercise (step test), on the euglobulin lysis time of women with retarded fetal development (92 cases), with physiologic pregnancy (50 cases) and non-pregnant women (20 cases) were studied. Both tests resulted in a pronounced shortening of euglobulin lysis time in the non-pregnant and to a lesser extent in the physiologic pregnancy cases (statistically significant after clamping of the cubital vein, statistically insignificant after the step test). In the etiologically heterogeneous group of pregnancy with retarded fetal development the response to both stimuli was weaker in comparison with the normal pregnancy group, and in many cases (58.7%) even "paradoxical", that is, instead of a rise in fibrinolytic activity, a fall was observed. These results indicate that in women with retarded fetal development fibrinolytic activity of the blood doses not rise as readily as it does in normal pregnancies. This applies both to local response (clamping test) and systemic response (step test), and is probably due to a fall in the plasminogen activator content of the venous vessel walls. As a working hypothesis, it is presumed that insufficiency of the plasminogen activator activity system facilitates the accumulation of fibrin deposits in the uterine--placental blood circulation, and contributes to retardation of intrauterine fetal growth.