A pregnant with known cardiac disease on warfarin for anticoagulation, presents soon after conception. What should be advised now?

Warfarin is teratogenic and can cause miscarriage, stillbihs, and fetal malformation, therefore to be avoided in first trimester For first trimester (for period of organogenesis)- give LMWH or unfractioned Heparin From 13 weeks till early term(36 weeks), put patient on warfarin after 36 weeks, we again put the patient on LMWH or unfractioned heparin. This is because since the patient can now go into labour and since warfarin (longer half life than LMWH) takes a longer time for its anticoagulant action to reverse, it may lead to bleeding complications during delivery or LSCS.