The causes of habitual abortion are complex. In addition to genetic, endocrine, infectious, anatomical factors, and some unexplained causes, recent studies have found that immune disorders are an important cause of the disease. Immune miscarriage can be divided into five types according to the type of immunopathology. The first type, is an alloimmune abortion caused by excessive leukocyte antigen compatibility of the couple, manifesting as negative for closed antibodies. The second type, which is caused by abnormal formation of antiphospholipid antibodies, is the case with your habitual miscarriage. Antiphospholipid antibody syndrome, which is the presence of fetal loss, thrombosis and thrombocytopenia along with the formation of abnormal antiphospholipid antibodies. The third type, is due to the production of antinuclear antibodies that damage placental cells. In the fourth type, it is mainly due to the production of various antibodies against germ cells, such as anti-sperm antibodies, anti-endometrial antibodies, anti-HCG antibodies, anti-ovarian antibodies, and anti-clear band antibodies. In the fifth type, it is due to excessive toxicity or number of one type of lymphocyte (i.e. NK cells) in the body that can kill the embryo. Why do positive antiphospholipid antibodies cause miscarriage? It turns out that phospholipids are important components of cell membranes, which play an important role in cell function, and when antiphospholipid antibodies are formed, they can destroy the phospholipid components of cell membranes, leading to cell damage. Especially, when it is damaged, the capillary epithelial cells of embryonic circulation will stimulate the coagulation system in the blood, leading to excessive blood clotting and the formation of thrombus, which will impair the blood circulation supplying embryonic nutrition, and the embryo will die due to ischemia and hypoxia. In addition, phospholipids are also responsible for the adhesion, implantation, and implantation of fertilized eggs in the endometrium. Therefore, when antiphospholipid antibodies are positive, the embryo will not adhere firmly to the uterine wall, causing habitual abortion and even infertility or IVF failure. There are dozens of phospholipids in the human body, but only six are closely related to reproductive function: cardiolipin, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol, phosphatidic acid and phosphatidylserine. Therefore, the presence of other antiphospholipid antibodies cannot be completely excluded in patients with negative anti-cardiolipid antibodies. On the other hand, antiphospholipid antibodies may also appear when the tissue cells in the body are damaged, such as viral infections, miscarriage, systemic lupus erythematosus and rheumatoid arthritis. Therefore, antiphospholipid antibodies are both the cause and the result of miscarriage. This reminds us that repeated testing and analysis are necessary for diagnosis. Since the main cause of miscarriage due to antiphospholipid antibodies is excessive blood clotting, the main treatment is to take blood thinners, i.e., anticoagulant drugs, commonly used are heparin and aspirin. Since heparin does not pass through the placenta, it is relatively safe for the fetus, while aspirin is a cautionary drug during pregnancy, and we usually use small doses, which are also quite safe for the fetus. It must be noted that during anticoagulation therapy, coagulation should be monitored regularly to avoid overkill. The duration of medication needs to be adjusted according to the monitoring indicators and is usually used for 3-5 months during pregnancy, and in some patients for up to 28 weeks. It has been proven that 86% of pregnancies due to habitual abortion caused by abnormal formation of antiphospholipid antibodies can be successful if regular anticoagulation therapy is administered before conception; however, if treatment is administered after a positive pregnancy test, 75% will have another abortion; if no anticoagulation therapy is administered at all, 97% of patients will have another abortion.