Impaired fibrinolytic response to exercise stress in normal pregnancy. Its possible role in the development of Shwartzman-type reactions

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.

Serum fibrin degradation products throughout normal pregnancy

Fibrin/fibrinogen degradation products in the serum of 169 healthy pregnant and 43 healthy non-pregnant subjects of a similar age group showed a significant increase throughout pregnancy, the highest levels being obtained in the third trimester. There was no correlation with plasma fibrinogen levels or euglobulin lysis times. Though these changes may be due to other alterations in pregnancy not primarily associated with fibrinolysis, it is possible that actual fibrinolysis is not decreased in late pregnancy, as has been previously asssumed.