What is infertility? According to the World Health Organization’s 2000 definition, infertility is diagnosed when a person has normal sexual function, has not used contraception for more than one year, and is unable to conceive a woman. The one-year period for determining the fertility of a couple is based on a large number of comprehensive statistical analyses and studies: the conception rate is 20% to 25% in the first month of marriage, 50% in 3 months, 72% in 6 months and 85% in 12 months. What is primary and secondary infertility? Primary infertility is when a man has never conceived any woman; secondary infertility is when he has conceived a female partner, but it is not related to whether or not that woman is his current partner or to the final outcome of the pregnancy. Men with secondary infertility usually have a better chance of future fertility. What are the main causes of male infertility? ① Insufficient testicular function: cryptorchidism, viral orchitis, testicular torsion, treatment for cytotoxicity (chemotherapy), radiotherapy, genetic abnormalities (congenital testicular hypoplasia, Y chromosome deletion); ② Endocrine abnormalities: Kalman’s syndrome, Prader-willy syndrome, pituitary gland abnormalities (adenomas, infections); ③ Obstruction of the male reproductive tract: congenital absence of the epididymal duct or the vas deferens, the Mullerian duct cysts, epididymal or vas deferens obstruction (infection, congenital), post-transinguinal or scrotal surgery; ④ drugs, environment, stress, systemic diseases; ⑤ varicocele, sexual dysfunction (e.g. erectile dysfunction); ⑥ congenital causes (idiopathic infertility).