Hi, thanks for asking in Healthcare Magic. Anticoagulants often increase the menstrual blood flow and the duration of menstruation but not in all. But usually the cause of heavy bleeding is improper dosage. A tight dosage regimen is followed according to blood clotting time in those under anti coagulant therapy. In case of Warfarin or Acitrom (Acenocoumarol) it is decided according to the INR (International Normalized Ratio) values. The INR value of these anticoagulants is 2 to 3. Values above this will result in severe bleeding. If the menstrual bleeding is severe even after proper dosing then, the other methods to reduce excessive bleeding are 1. Hormone therapy. 2. Endometrial ablation. 3. Intra Uterine Contraceptive Device (IUCD). Hormonal therapy with either estrogen or progesterone can increase the risk of thrombo embolism for your wife. Endometrial ablation (destruction of uterine lining) is suitable only for women who does not want further pregnancy as the chances of conceiving after this procedure are reduced. IUCD like Mirena contain Progesterone which again can increase the risk of thrombo embolism. Non hormonal IUCD like copper T may be more preferable. However Warfarin or Acenocoumarol should be substituted to Heparin in case of pregnancy as they both can damage the fetus. I hope this is useful to you.