The most important common factor in determining fertility is age. Men and women enter the reproductive period after puberty, women can not give birth after menopause, male fertility also declines with age (but not completely lost), even in the age of active fertility, age will Has an impact on fertility. The chances of male and female reproductive disorders are equal (40%). The probability of a problem with both men and women is 20%. The most common cause of male infertility is that the number of sperm is too small. When the injected semen contains less than 20 million sperm per milliliter, it is very difficult to conceive. Other causes include a large number of sperm defects and blockage of the tubing that transports the sperm. This may be due to abnormal testicular development (including testicular decline), infection (including sexually transmitted diseases), radiation, chemicals, severe malnutrition, and systemic failure. Steroid hormones also inhibit sperm production by inhibiting the secretion of gonadotropins. The most common cause of infertility in women is the inability to ovulate and the obstruction of the fallopian tubes for a variety of reasons. More obvious are reproductive organ defects, hormone secretion disorders, ovarian disease, severe malnutrition, chronic diseases, drug addiction, and pelvic infections causing fallopian tube scar formation. Some rare cases may also be psychological, and if the desire for conception develops into anxiety, it will be counterproductive. When we focus on new life, we should not ignore the problem of infertility. Infertility refers to the inability to conceive (usually one year) for a certain period of time, and infertility refers to permanent infertility. The total population of the world may be oversupplied, but for a couple, the inability to have children can make them feel bad. In the United States, about one in every ten couples still can’t get their children after working hard for a year or more. In addition, one out of every ten couples wants to have more children, but they can’t do anything about it. Among married women aged 20 to 24 (best growth period), infertility rose by 177% between 1965 and 1982, many of which were due to increased pelvic infections.