Recurrent miscarriage, formerly known as habitual miscarriage, refers to three or more consecutive spontaneous abortions. Although it is defined as three or more consecutive miscarriages, most experts believe that two consecutive miscarriages should be taken seriously and evaluated because the risk of recurrent miscarriage is similar to that of three. The common causes of early miscarriage are chromosomal abnormalities of the embryo, luteal insufficiency, hypothyroidism, and immune abnormalities, while the common causes of late miscarriage are uterine malformation or dysplasia, relaxation of the endocervix, and uterine fibroids. The etiology of recurrent miscarriage is very complex and the diagnosis requires the participation of both spouses and joint examination. The treatment principle of RSA is to treat the etiology: 1. chromosomal abnormalities: For patients with chromosomal abnormalities, genetic counseling is the main concern. Pre-implantation genetic diagnosis (PGD, i.e., third-generation IVF) technology can be performed for some genetic disorders, and embryos without genetic defects can be selected for transfer with a view to obtaining a healthy baby. 2, anatomical abnormalities of the reproductive tract: such as uterine anomalies, hysteroscopic separation of adhesions, cervical insufficiency, cervical cerclage at 16-22 weeks of pregnancy. Endocrine therapy: Luteinizing support can be given for luteal insufficiency, bromocriptine for hyperprolactinemia, and eugenol/retinol for hypothyroidism. 4.Infection factor treatment: For those who have infections, choose sensitive drugs for different pathogens (such as Chlamydia, various viruses, Toxoplasma, etc.). 5, immunotherapy: rheumatic immune factors such as anti-nuclear antibodies, anti-cardiolipin antibody positive people can be treated with glucocorticoids.