The findings show that antenatal hypoxia has a pronounced effect on the blood coagulation system. The re- vealed changes in hemostasis of hypocoagulant orientation: the thrombin time characterizing the final phase of coagulation extends the level of fibrinogen decreases, and the plasma tolerance to heparin increases. These changes are mainly found in the embryonic period under the exposure of the hypoxia factor. It has been established that prenatal hypoxia contributes to the slowing down of the blood coagulation process in the early periods of postnatal ontogeny in offspring.