Definition of male infertility The World Health Organization defines male infertility as a condition in which a couple has lived together for more than one year without using any contraception and the female partner is infertile due to male factors. Male infertility is not an independent disease, but is the result of one or many diseases and/or factors. Factors affecting male infertility 1. Infertility duration Under normal circumstances, couples with normal fertility have a 20% to 25% pregnancy rate in a single month, a 75% pregnancy rate in six months, and a 90% pregnancy rate in one year. Infertility for more than 4 years, then the monthly pregnancy rate is only 1.5%. 2, primary or secondary infertility Primary male infertility is mostly due to hypospermia or disorders of spermatogenesis, and can also be due to congenital developmental abnormalities. Secondary male infertility is mostly caused by acquired factors, including medical injury, reproductive system infection, etc. Usually, fertility can be restored through treatment or through assisted reproductive technology to obtain their own offspring. 3. Semen analysis is an important basis for assessing male fertility, and abnormal results indicate reduced fertility. The most closely related semen parameters to fertility are total sperm count and viability, while sperm morphological testing is an important reference for predicting the success rate of in vitro fertilization-embryo transfer. 4. Age and fertility of the female partner The fertility of the female partner at the age of 35 is 50% of that at the age of 25, decreasing to 25% by the age of 38, and can further decrease to less than 5% beyond the age of 40. Despite the progress and optimization of various assisted reproductive technologies, the age of the woman is still one of the most important factors affecting the success rate of pregnancy.