What is recurrent miscarriage? According to the latest medical opinion, recurrent miscarriage (RSA) is defined as 2 or more failed pregnancies within 28 weeks, and 3 or more failed assisted reproductive implants also fall under this category. What causes recurrent miscarriage? The causes of recurrent miscarriage are analyzed as follows: genetic, immunological, pre-thrombotic state, endocrine, anatomical, infectious and psychological factors. 1, genetic (chromosomal) factors The smaller the gestational week of miscarriage, the greater the possibility of chromosomal factors, if it is about 7 weeks of gestation, then chromosomal factors will account for about half, mostly embryonic chromosomal occasional errors, most of the chromosomes of both spouses are normal. However, if there are 2 or more abortions, both domestic and international guidelines recommend checking the chromosomes of the aborted tissue and the chromosomes of both spouses, and it is possible that one of the parties has abnormal chromosome structure in order to find the cause of abortion. 2, immune factors 1, alloimmune: maternal recognition of the paternal antigen of the embryo is abnormal and triggers strong rejection of the fetus by the maternal immune system. 2. Autoimmunity: mainly related to autoimmune diseases and autoantibodies such as antiphospholipid antibody syndrome, systemic lupus erythematosus and dry syndrome. Pre-thrombotic state: The hypercoagulable state of blood during pregnancy makes the uteroplacenta susceptible to local microthrombosis or even placental infarction, which decreases the blood supply to the placenta and causes embryonic ischemia and hypoxia, eventually leading to miscarriage due to embryonic dysplasia. The diagnosis can be made by detecting pre-thrombotic state markers. 4. Endocrine factors The Royal College of Obstetricians and Gynecologists guidelines suggest that polycystic ovary syndrome may increase the incidence of spontaneous abortion. The American Society for Reproductive Medicine believes that hyperprolactinemia is associated with RSA. In addition, maternal endocrine disorders such as uncontrolled diabetes mellitus, thyroid disease, and luteal insufficiency are associated with the development of RSA. The incidence of early miscarriage due to polycystic ovary syndrome and luteal insufficiency is high. Elevated basal follicle stimulating hormone and luteinizing hormone also increase the incidence of recurrent miscarriage. 5, anatomical abnormalities of the uterus including uterine malformation, cervical insufficiency, uterine adhesions, uterine fibroids, adenomyosis, etc. RSA due to anatomical factors is mostly late miscarriage or preterm delivery. Especially, cervical insufficiency is an important cause of late spontaneous abortion. 6. Infectious factors Bacterial vaginosis patients have a higher incidence of late pregnancy miscarriage and preterm delivery, and endometritis or cervicitis caused by Chlamydia trachomatis and Mycoplasma solium can lead to miscarriage. Toxoplasma gondii, herpes simplex virus, rubella virus, and cytomegalovirus infections are associated with miscarriage. Therefore, it is recommended that RSA patients with reproductive tract infections should undergo targeted treatment before conception and conceive after the infection is controlled. 7, unknown factors RSA is also associated with many other unknown factors, including adverse environmental factors, adverse psychological factors, such as female mental tension, negative emotional depression, as well as fear and sadness, etc. All kinds of adverse psychological stimuli can affect the neuroendocrine system, making the internal environment of the body change, thus affecting the normal development of the embryo. In fact, recurrent miscarriage is not scary, what is scary is not to pay attention to the recurrence of miscarriage. If active examination and treatment, most people can obtain a better pregnancy outcome.