Antiphospholipid syndrome is a rare autoimmune disease that has been closely linked to some cases of recurrent miscarriage. This syndrome increases blood clotting. It can cause dangerous blood clots (thrombosis) and problems with blood flow. Sometimes the only sign of this syndrome is an early miscarriage. Or, later in the pregnancy, this syndrome may lead to problems with the placenta or preeclampsia, which may cause pregnancy loss.

This syndrome is treated with blood-thinning medicines to prevent clotting problems and pregnancy loss. These medicines may include heparin, aspirin, or both.

Other types of blood-clotting disorders can cause similar pregnancy problems. Your doctor can test for blood-clotting disorders.