Pregnancy and mechanical valve prostheses: a high-risk situation for the mother and the fetus.

Thirty-eight women with mechanical valve prostheses had a total of 47 pregnancies. All patients were on oral anticoagulants before pregnancy. A high incidence of complications was seen in both the mothers and the fetuses. The rate of spontaneous abortion was 23.4% (11/47), and 2 of the 36 newborns had chondrodysplasia punctata. Three of the women (7.9%) had acute valvular thrombosis; 1 died after replacement of the thrombosed valve. Thus, the overall mortality for the series was 2.6%. More complications were observed in the fetuses and infants of women treated with oral anticoagulants during pregnancy than in women treated with heparin. However, the mothers had more complications with heparin anticoagulation. Neither heparin nor oral anticoagulants clearly proved superior as the anticoagulation regimen of choice for pregnant women with mechanical valves. Counseling before conception occurs and avoidance of pregnancy are recommended for women with mechanical valve prostheses because of the high risk of serious or fatal complications in the mother and fetus. Use of tissue valves in women of childbearing age who desire to have children also seems advisable, even with the possibility of having to undergo another operation as a result of degeneration of the valve tissue.