An abnormal antibody that has been associated with frequent pregnancy loss. The lupus anticoagulant is often found in people with lupus erythematosus, but may also be found in those who do not have true lupus erythematosus. Anticoagulants are substances that prevent the blood from clotting normally. The lupus anticoagulant has that effect on one test of blood clotting function. However, the lupus anticoagulant has the opposite effect in pregnant women: it causes abnormal blood clots to form. There are treatments for this and it is possible to have a normal baby despite the presence of the lupus anticoagulant.