Introduction
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One of the causes of obstetric hemorrhages is toxicosis in the second half of pregnancy accompanied by a chronic form of disseminated intravascular coagulation syndrome, hypercoagulation and increased aggregation activity of platelets.

Methods
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To assess the functional state of the hemostasis system we used our devised test with local ischemia of the upper extremity. The analysis of the coagulation, vascular and thrombocytic components of hemostasis and fibrinolysis was made on the basis of parameters of the blood aggregate state obtained using the method of haemoviscoelastography.

Results
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We examined 30 healthy pregnant women in the age range 20--31 years (control group), and 30 pregnant women with revealed late toxicosis of different severity degree (nephropathy of II degree, 10 women; nephropathy of III degree, 20 women). While analyzing the functional state of the hemostasis system in healthy pregnant women we distinguished two types of response to the test: compensated type (1) in 30% and subcompensated type (2) in 70%. The pregnant women suffering from late toxicosis were registered to have a subcompensated type of the hemostasis system response (3) in 20% of cases and a decompensated type (4) in 80% of cases. The functional test in group 1 resulted in decreased aggregation activity of platelets, reduced activity of the I and II phases of blood coagulation (elevation of *r*and *k*) and activation of the fibrinolytic system. Group 2 is noted to have enhanced aggregation activity of platelets, enhanced thrombin activity and acceleration of the thrombin formation and activation of II and III coagulation phases. The total fibrinolytic blood activity was reduced by 42%.

Conclusion
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Late toxicosis is therefore accompanied by changes in the hemostasis system, causing exhaustion of compensatory potentials of the regulation system of the blood aggregate state and promoting a high risk of thrombohemorrhagic complications during delivery and in the postpartum period.
