Infertility is the inability to father children after a period of 12 months or more keeping unprotected sex. This term should be distinguished from sterility, which is the absolute inability to achieve pregnancy. According to the World Health Organization, infertility affects 15% of couples. In approximately 40% of cases, it is male infertility; in another 40%, the problem comes from the woman, and the remaining 20% either of the two, or unspecified causes. The causes may be varied: genetics, immune, endocrine, toxic, infectious, etc. So both partners must undergo medical tests. Treatment may include techniques such as in vitro fertilization, artificial insemination, transfer of zygotes to the fallopian tubes, intracytoplasmic sperm injection.