pregnancy outcome after mechanical mitral valve replacement: a prospective study

background: pregnant patients with mechanical heart valves require anticoagulation. the risk of bleeding and embryopathy associated with oral anticoagulants must be weighed against the risk of valve thrombosis. methods: in this prospective study, undertaken between 1999 and 2009, 53 pregnancies (47 women with mechanical mitral valves; 29.8 ± 4.8 years old) were studied. patients were divided into two groups: group i (n = 43) received warfarin throughout the pregnancy, while group ii (n = 10) received heparin in the first trimester and then warfarin until the 36th week. results: thirty-two (60.4%) pregnancies resulted in live births, whereas 18 (34%) abortions, 2 (3.8%) stillbirths, and one (1.9%) maternal death occurred. in group i, there were 26 (60.5%) live births, one (2.3%) stillbirth, and 15 (34.9%) abortions. in group ii, there were 6 (60%) live births, one (10%) stillbirth, and 3 (30%) abortions. there were no significant differences between the two groups in terms of fetal outcome. thirty-nine (90.7%) of the pregnancies in group i and 50% of those in group ii (p value = 0.001) were without complications. there were no congenital malformations in the two groups. conclusion: fetal outcome was almost the same between the warfarin and heparin regimens. in maternal outcome, the w arfarin regimen is safer than heparin.