Habitual miscarriage is a spontaneous miscarriage with three or more miscarriages. The most common causes are as follows: i. Chromosomal abnormalities: Miscarriage caused by chromosomal abnormalities in both or one of the spouses or embryos. It is a necessary examination item for habitual miscarriage, and chromosomal examination of the embryo is also required if the miscarried embryo can be obtained. This is because some embryos with chromosomal abnormalities may have normal chromosomes in their parents. In case of chromosomal abnormalities, it should be determined whether the pregnancy can be repeated according to the type of abnormality, and if it can be repeated, prenatal diagnosis should be done to ensure eugenics. The anatomical anomalies of reproductive tract include congenital abnormalities of uterine development and uterine anomalies caused by acquired uterine diseases, such as longitudinal uterus, unicornuate uterus, uterine adhesions caused by multiple abortions or uterine infections, submucosal muscles of the uterus, endometrial polyps, loose cervical opening, etc. In case of incomplete mediastinum, surgical treatment should be chosen according to the size of the mediastinum and its influence on the uterine cavity, and adhesiolysis is feasible for those with uterine cavity adhesions, and submucosal fibroids and polyps should be removed. Endocrine dysfunction: Luteinizing insufficiency and hyperprolactinemia are common, and such infertility causes of miscarriage should be diagnosed and treated before conception. Reproductive tract infection: mainly refers to various bacterial infections, toxoplasmosis, cytomegalovirus and herpes simplex virus infections. These infections may be transmitted to the fetus through the placental barrier leading to fetal infection death or malformation. They need to be cured before conception in order to avoid the trauma of induced abortion after pregnancy. Immune diseases: The common one is miscarriage caused by anti-cardiolipin antibodies. Anti-cardiolipin antibodies eventually lead to placental vascular embolism through different mechanisms, so that the fetus does not get enough blood supply and eventually stops developing and miscarries. Treatment can be based on the condition of glucocorticoids and aspirin alone or in combination, and anticoagulation therapy with low fraction of heparin can be used during pregnancy, and coagulation indicators are closely tested. Unexplained habitual abortion: also known as homozygous immune abortion. It refers to the miscarriage excluding all the above factors. It accounts for 40-80% of habitual abortions. These patients can be given a course of active immunotherapy before conception, conceive as soon as possible within three months after the first course of treatment, and then another course of treatment after conception, and about 90% of these patients finally succeed in pregnancy after immunotherapy. In summary, it can be seen that the etiology of miscarriage is complex, and many patients’ miscarriages are not caused by a single factor. Therefore, comprehensive etiological examination and integrated treatment are emphasized, including pre-conception measures to prevent miscarriage, such as taking appropriate amounts of multivitamins and consuming less fish and seafood with high mercury content. Avoiding exposure to toxic substances and radiation, preventing all kinds of infections, etc. After systematic examination and treatment, most of the miscarriages can be successfully conceived.