In the modern world, the problem of maintaining a woman's reproductive potential and preserving the resulting pregnancy comes to the fore. An important aspect remains the increasing number of concomitant extragenital diseases. The most common pathology of the cardiovascular and respiratory systems. A rare and often fatal complication is Eisenmenger's syndrome. Eisenmenger's syndrome is a pathological process that occurs due to bidirectional blood discharge or right-left blood discharge due to the presence of a message between the right and left parts of the heart, clinically manifested by severe pulmonary hypertension with diffuse cyanosis. It occurs against the background of an existing decompensated heart defect - a defect of the atrial septum, interventricular septum, open arterial duct, anomalies of the pulmonary veins. Previously, it was believe that the threat of developing Eisenmenger syndrome is an absolute indication for termination of pregnancy, and this pathology is not compatible with gestation. Currently, the effect of pregnancy on the cardiovascular system has been study and recommendations for the management of such patients have been develop. It found that due to an increase in the volume of circulating blood, cardiac output, a decrease in total peripheral resistance and blood pressure, there is an increase in the load on the cardiovascular system and a change in the pharmacokinetics of drugs, which leads to a revision of the treatment tactics used before pregnancy. The situation is aggravated by an increase in blood clotting factors, fibrinogen, platelet aggregation and a decrease in fibrinolysis factors, which, together with the restriction of taking low-molecular-weight heparins due to the tendency of patients with Eisenmenger syndrome to bleeding and thrombosis, causes difficulties in determining the tactics of patient management, emphasizing the importance and relevance of the problem.