After marriage, if neither party has a desire not to have children, and they have cohabited for more than a year with normal sexual activity without using contraception yet are still unable to conceive, they are diagnosed with infertility.

Infertility pertains to females, and sterility pertains to males. If infertility is confirmed, one can first visit a local reproductive center for consultation. Currently, the technology and diagnostic methods related to reproduction are mostly uniform everywhere, involving a screening process. Therefore, one can begin by screening at a local reproductive center to identify some possible causes for not conceiving, including issues like ovulatory disorders in the female, fallopian tube factors, the presence of endometriosis, uterine abnormalities, immune factors, and the normalcy of the male sperm. After screening the causes, consider monitoring ovulation and guiding intercourse, or explore assisted reproductive techniques, including artificial insemination and in vitro fertilization (IVF). The best hospital for assisted reproduction in the country is Peking University Third Hospital. However, the level of assisted reproduction technology is similar nationwide, and facilities are continuously learning and sharing techniques, so one can choose a local center based on personal circumstances.