To evaluate the efficiency of different types of antithrombotic therapy in the prevention of gestational complications in patients with thrombophilia, the authors examined 671 patients, including 117 and 554 patients who were treated in the pregravid period and only in the second and third trimesters of pregnancy, respectively. According to the type of antithrombotic therapy, there were 3 subgroups: 1) patients who were treated with low-molecular-weight heparins (LMWH); 2) those who received LMWH in combination with acetylsalicylic acid preparations; and 3) those who took heparinoids (sulodexide). All the drugs were given in the minimum therapeutic doses. Simple envelope randomization is a means of sampling. Therapeutic efficacy was evaluated from the hemostatic and hemodynamic changes in the maternal-placental-fetal system. The study has ascertained that sulodexide monotherapy both in the pregravid stage and during pregnancy is most preferred since it makes it possible to substantially improve total blood clotting potential, thus reducing the proportion of severe gestational complications.