I. What is recurrent miscarriage? Repeated miscarriage refers to 3 or more consecutive miscarriages in women of childbearing age before 28 weeks of gestation with fetal weight below 1000g,? The embryo automatically stops developing and miscarries. 2. Causes of recurrent miscarriage? The etiology and pathological mechanism of recurrent miscarriage are very complicated, and a comprehensive examination is needed to find the cause. About 50% of them have no clear cause and belong to recurrent miscarriage of unknown origin, and immune factors play an important role in the pathological mechanism of recurrent miscarriage of unknown origin. The common causes are as follows: 1) uterine factors: uterine malformations, uterine adhesions, benign and malignant tumors of the uterus can lead to endometrial dysplasia, insufficient blood supply to the uterus affecting the development of the fetal placenta and leading to miscarriage. Cervical insufficiency, i.e. endocervical insufficiency or endocervical laxity, is the main cause of recurrent miscarriage in mid-pregnancy. (2) Genetic factors: The rate of chromosomal abnormalities in couples with recurrent miscarriage is about 3.2%-4.9%, which mainly manifests as embryonic abortion and recurrent miscarriage in early pregnancy. Karyotype analysis of miscarried embryo tissues revealed that 22%-61% of miscarried embryos have chromosomal abnormalities, and spontaneous miscarriage due to chromosomal abnormalities or genetic abnormalities is a form of natural selection in human evolution. (3) Immunological factors: The relationship between immunological factors and recurrent miscarriage is attracting more and more attention. Repeated miscarriages that were thought to be of unknown cause in the past are now considered to be related to immune factors, and about 20% of repeated miscarriages are caused by immune factors. Tests mainly include anticardiolipin antibodies, antinuclear antibodies, lupus anticoagulant, β2-glycoprotein I antibodies, antithyroglobulin antibodies, antithyroid peroxidase antibodies, etc. (4) Endocrine factors: Common endocrine abnormalities include luteal insufficiency, hyperprolactinemia, hypothyroidism, polycystic ovary syndrome, and severe diabetes mellitus. (5) Infection: Infection during pregnancy not only harms the mother, but certain infections can also have serious effects on the fetus and newborn. In addition to possibly causing miscarriage, premature birth or stillbirth, they can also cause various malformations and mentally retarded children, thus affecting the quality of the population. The main tests include TORCH, i.e. the four eugenic tests (toxoplasmosis, cytomegalovirus, rubella virus, herpes simplex virus), as well as chlamydia and gonococcus. (6) ABO+RH blood group incompatibility between mother and child: blood group incompatibility between pregnant woman and fetus will result in alloimmune disease, which in turn will cause miscarriage. 7) Insufficient immunosuppression: abnormal immune response to paternal antigens of the embryo, maternal rejection of the fetus, manifested as negative closed antibody. 8) Systemic diseases: severe anemia or heart failure, diabetes mellitus, hypertension, liver and kidney diseases, poor coagulation function, etc. 9) Bad habits: excessive smoking, alcoholism, excessive coffee, drug and medicine dependence, exposure to toxic substances. 10) Male factor: poor semen quality, or sperm DNA damage. III. Treatment of repetitive miscarriage Treatment for the etiology, if the cause of miscarriage is not found, comprehensive treatment based on clinical experience is needed. (1) Etiological treatment: Give etiological treatment if the cause is found according to the above examination. (1) Give heparin sodium and aspirin if the relevant antibody is positive. (2) Immunotherapy, such as closed antibody negative: clinically, lymphocyte immunotherapy of the partner is used to induce the maternal alloimmune response, resulting in the appearance of closed antibodies and microlymphocytotoxic antibodies, so that the maternal immune system is less likely to produce immune attack on the fetus and the pregnancy continues. (iii) Uterine insufficiency: cervical cerclage is given at 12 to 17 weeks of gestation. ④Uterine malformation can be treated by surgical correction, large uterine fibroids can be removed, and uterine adhesions can be treated with surgery and estrogen. ⑤Patients with hyperprolactinemia can be given bromocriptine to control prolactin at normal levels by excluding pituitary adenomas. (6) Supplementary therapy such as eugenol should be given to patients with hypothyroidism. (7) Patients with abortion due to infection are given anti-infection treatment until the relevant indexes turn negative. (8) Systemic diseases such as diabetes mellitus and hypertension should be treated with hypoglycemic and antihypertensive therapy. 2) Fetal preservation treatment: for patients with preterm abortion and previous history of spontaneous abortion, fetal preservation treatment should be given as early as possible after pregnancy. 3) Regular tests such as blood HCG (chorionic gonadotropin), prolactin, progesterone, etc. If the test result is abnormal, it indicates the possibility of miscarriage and can be treated in advance. 4) Pay attention to rest, strengthen nutrition, and avoid all stimulating factors that can cause uterine contractions as much as possible. (5) Monitor the antibody potency of mother and child with blood group incompatibility during pregnancy, monitor closely during pregnancy, if the antibody potency increases, terminate the pregnancy in time when the fetus is mature. (6) Treatment is required for male partner with abnormal semen. Patients with recurrent abortion should take contraceptive measures first, and then get pregnant after comprehensive examination and targeted treatment to avoid recurrence of spontaneous abortion.