Pregnancy failure (spontaneous abortion and fetal abortion) is a common problem with various causes, mostly due to chromosomal abnormalities (more than 50%) in the early stages (within 12 weeks). The main male factors for pregnancy failure or recurrent pregnancy failure (3 or more consecutive pregnancies) are: 1. Chromosomal abnormalities (somatic cells or sperm, karyotype analysis of lymphocytes for the former and multicolor fluorescence in situ hybridization of sperm for the latter), including numerical abnormalities (e.g., one extra or one less chromosome), structural abnormalities (e.g., mutual translocation of chromosomal segments, Robertsonian translocation, interarm inversion, etc.). The relationship between chromosomal polymorphisms (e.g., large or small Y, size and presence of follower, growth or shortening of secondary constrictions, etc.) and pregnancy failure is unclear. 2. Sperm DNA damage, i.e. single or double strand breaks in sperm DNA occur. The causes include varicocele, ionizing radiation, reproductive toxic drugs, abnormal oxidation reaction, lack of fisetin and smoking, etc. Sperm with DNA damage can still be inseminated, and the oocyte has the function of repairing sperm DNA after sperm-egg union, and if it is completely repaired, it will continue to develop and deliver a normal pregnancy. If the sperm DNA damage is severe, or if the oocyte is weak in repairing it (related to the age of the female partner), the result may be spontaneous abortion, fetal abortion or embryonic malformation. Methods to detect sperm DNA damage include the comet test (Comet) and the sperm chromatin diffusion test (SCD). 3. Abnormalities in routine semen parameters, such as sperm concentration (oligospermia), sperm motility (weak sperm) and sperm morphology (high sperm malformation) are not clearly associated with pregnancy failure. 4. Genitourinary tract infections, such as orchitis, epididymitis, prostatitis, vesiculitis and urethritis, are not clearly related to pregnancy failure.