While maternal outcome in these patients depends on her state of health, fetal outcome is related to the degree of cyanosis in maternal blood. One major problem in these pregnancies is the high risk of thrombo-embolism. The mechanism is the sluggish circulation and high viscosity of blood. In this even more complex syndrome of patients who have only one functioning ventricle , experience is much more limited. Maternal outcome depends on the pulmonary vascular resistance, with severe elevations of resistance resulting in a high maternal mortality.
Fetal outcome is dependent on the severity of maternal cyanosis.
Oxygen in maternal blood is exchanged across the placenta and supplies the growing fetus. When cyanosis is severe, the oxygen content in maternal blood is low. As a result, the fetus receives lesser oxygen and develops severe growth retardation and asphyxia. There are few case reports of successful pregnancies in patients with Ebstein's anomaly and in Transposition of Great Arteries after the Mustard operation. Even heart transplant recepients can undergo pregnancy, the problems being more related to managing immunosuppressive therapy rather than cardiac function.