A 26 yr. old woman with a known case of mitral valve replacement done 2 years back for severe MS, currently on therapeutic anticoagulation with 5mg daily Warfarin, wants to conceive and has come for preconception counseling. All are true except:

Ans. B. Warfarin should be stopped periconceptionally and switch over to heparinThe pregnancy outcome and prognosis of mitral stenosis is related to the functional capacity of the woman with the mortality rising considerably in the NYHA class III & IV group. Prognosis is also worsened when the mitral valve area is <2cm2. Therefore, pregnancy is contraindicated in these women and termination is advised. Such lesions should be treated, and cardiac status optimized before conceiving.Women who have undergone valve replacement are on therapeutic anticoagulation with warfarin when they have a metallic valve in situ. Warfarin is the most effective for preventing maternal thromboembolic complications. But warfarin also leads to embryopathy, 6%, the risk being highest when the mean daily dose exceeded 5mg.Therefore, warfarin is stopped once pregnancy is confirmed and heparin is substituted till 12 weeks, following which warfarin is restarted for the remainder of pregnancy till 36 weeks. Warfarin is not recommended during labor as it can lead to post-partum hemorrhage.Beyond 36 weeks' heparin is started again because its effect can be controlled, it does not affect the synthesis of clotting factors and a specific antidote in the form of protamine sulfate is available. Heparin is also discontinued just before delivery.Anticoagulant therapy with warfarin or heparin may be restarted 6hr following vaginal delivery or 24hr after caesarean section.