Infertility is defined as a person who has lived together as a couple for two years after marriage and has had normal sexual intercourse without conception. The current international definition of infertility is not consistent; the American Infertility Society sets the time after marriage at 1 year, and the Japanese and International Society of Obstetrics and Gynecology set the time after marriage at 2 years. However, if the age of late marriage is relatively high (over 30 years old) and cohabitation after 1 year of marriage is not pregnant, early diagnosis and treatment according to infertility should also be done to avoid delaying conception. Because the most fertile period of women is around 25 years old, after that, their fertility decreases slowly, and after 35 years old, their fertility decreases rapidly, and after 45 years old, there are few conceptions. There are many ways to classify infertility, the main ones are: (1) Classification according to whether the cause of infertility is male or female: it can be divided into two types of male infertility and female infertility. Male infertility is divided into two cases: one is that the male partner is unable to conceive because of azoospermia, which is called male infertility; the other is that although the female partner can conceive, the sperm quality is poor, so that the embryo after conception cannot develop into a normal fetus and dies in the middle, which is called male infertility, both of which can be collectively called male infertility. (2) Classification according to whether conception has occurred: can be divided into primary infertility and secondary infertility. The former refers to those who have never had a pregnancy after living together without contraception and having a normal sexual life; the latter refers to those who have had a pregnancy, including premature birth, miscarriage, full-term pregnancy or other abnormal pregnancy, and then failed to conceive again after having a normal sexual life for more than two years. (3) Classification according to the possibility of pregnancy after treatment: it can be divided into absolute infertility and relative infertility. The former refers to a couple in which one of the partners has congenital or acquired anatomical or physiological defects with no hope of successful treatment, such as congenital absence of vagina or uterus or the uterus has been removed due to lesions; the male partner has congenital azoospermia or acquired diseases that make the testes incompetent to produce sperm. Relative infertility refers to infertility in which the fertility of one of the couple is reduced or prevented from conception due to certain factors, and after treatment, there may be a chance of conception. (4) According to the physiological and pathological characteristics of infertility, it can be divided into physiological infertility and pathological infertility. The former refers to infertility caused by physiological characteristics during puberty, pregnancy, lactation, menopause, etc.; the latter refers to infertility caused by certain physiological disorders or organic lesions of reproductive organs such as tumors, inflammation, venereal diseases, tuberculosis, etc. (5) Classification according to the lesion organ causing infertility: it can be divided into local infertility and systemic infertility. The former refers to infertility caused by local lesions of reproductive organs, such as the uterus, fallopian tubes, ovaries and adjacent tissues and organs of the pelvis; the latter refers to infertility caused by systemic diseases, such as endocrine disorders, nutritional and metabolic disorders, and excessive medication of psychiatric patients. In recent years, with the progress of research in physiology, it is increasingly felt that the causal relationship causing infertility cannot be separated, thus the above-mentioned classification methods for infertility are still not perfect. What are the systemic causes of female infertility? Although conception is an extremely common physiological phenomenon, it is an extremely complex physiological process. Therefore, when analyzing the causes of infertility, we should consider the infertile couple as a reproductive unit, and should not put all the blame on the woman. The female partner should not be blamed for all of them. According to a survey conducted by the World Health Organization (WHO) in Asia in 1990, the female factor alone accounted for 44%, the male factor alone accounted for 13%, the male and female factors accounted for 24%, and the unknown cause accounted for 19%.