The causes of recurrent miscarriage are very complex and can be either a single factor causing miscarriage or a confounding multifactorial cause. The diagnosis of recurrent miscarriage is an exclusionary diagnosis, therefore, a comprehensive and systematic screening of the five major causes of recurrent miscarriage should be performed. 1, genetic factors: chromosome examination of both sides (embryonic chorionic villus chromosome examination); 2, reproductive tract anatomical factors: ultrasound, hysterosalpingogram, hysteroscopy, laparoscopy; 3, reproductive endocrine factors: sex hormones, anti-mullerian hormone, inhibin B, methyl work; 4, reproductive tract infection factors: bacterial vaginosis, chlamydia (mycoplasma), gonorrhea, eugenics 10 5, immune factors: ① autoantibodies Anti-cardiolipin antibody, β2-glycoprotein I-Ab, lupus anticoagulant, anti-nuclear antibody, anti-deoxyribonucleoprotein antibody, deoxyribonucleic acid antibody, anti-double-stranded DNA antibody, anti extractable nuclear antigen antibody profile, anti-thyroid antibody. ② homologous antibodies: closed antibodies; ③ cellular immune examination: CD16+CD56 (NK cells), CD19 (B lymphocytes); ④ infertility antibodies: anti-sperm antibodies, anti-endometrial antibodies, anti-ovarian antibodies, anti-HCG antibodies, anti-ovarian cell zona pellucida antibodies, anti-trophoblast membrane antibodies; ⑤ blood type and antibodies: female “O If necessary, blood group antibody test should be done when the female partner is type “O” and the male partner is type A/B/AB. 6) Coagulation function: D-dimer, coagulation 4, protein C, protein S, homocysteine, antithrombin III, blood rheology 14, platelet aggregation, thromboelastography. 6, male side examination: semen full set, anti-sperm antibodies, trace elements 7 items, chromosomes. Weak and deformed spermatozoa check Y chromosome microdeletion, sex hormone 4 items, etc.