Pregnancy in women with mechanical prosthetic valves carried an increased risk of thromboembolic complications due to changes in hemostasis. The major task in selecting an artificial valve is to weigh the advantage of durability and the disadvantages of the risks of thromboembolism and anticoagulant treatment inherent in mechanical prostheses on the one hand with the advantage of low thrombogenicity and the disadvantage of abbreviated durability of bioprostheses on the other. Anticoagulation prophylaxis with both warfarin and heparin may be associated with important fetal and maternal side effects