The World Health Organization defines infertility as the failure of a couple of reproductive age to conceive after having normal, regular sex for at least one year without using any contraception. The incidence of infertility is increasing year by year, and infertility has become a worldwide medical and social problem, and is one of the important diseases that endanger human reproductive health in the 21st century. The causes of female infertility are many and complex, mainly including the following major categories: age factors Age is an important factor that independently affects female fertility. As age increases, it may be due to a decrease in the number and quality of eggs, a decrease in the fertilization ability of eggs and the ability to grow embryos, and an increase in the chance of chromosomal abnormalities, making the chances of successful conception decrease year by year. Abnormal ovulatory function Irregular menstrual cycles or amenorrhea are common manifestations of abnormal ovulatory function. 15-21% of women with infertility are ovulatory disorders. Normal ovulation depends on the dynamic balance of the hormones involved in the hypothalamic-pituitary-gonadal axis, so abnormal ovulation is a manifestation of abnormal function of these systems. Tubal factors The peristalsis of the smooth muscle of the fallopian tubes, the oscillation of the epithelial cilia and the patency of the fallopian tubes are necessary for natural conception. Uterine factors Uterine infertility mainly includes the following conditions, congenital uterine agenesis, congenital uterine malformation, uterine fibroids, adenomyosis, endometritis, endometrial polyps, atypical hyperplasia of the endometrium, etc., which prevent sperm from moving up and fertilized eggs from being laid and planted. Endometriosis and infertility 30-58% of infertility patients are combined with endometriosis, which is closely related to infertility. Endometriosis causes pelvic adhesions, tubal obstruction or prevents the fallopian tubes from transporting eggs, interferes with ovarian endocrine function and ovulation, and affects sperm-egg union and embryo implantation. Infertility of the lower reproductive tract and the cervix Abnormalities in the development of the vulva and vagina, as well as trauma and surgical scar narrowing, can affect the upstream movement of sperm and the union of the egg, while abnormalities in the anatomy of the cervical canal and the secretion function of the glandular epithelium can affect the survival, upstream movement and storage of sperm and cause infertility. Immunologic infertility is a complex immune response in all aspects of natural conception. The neuroendocrine and immune systems influence reproductive endocrinology and regulate the fertility process through the interaction of peptide hormones, neurotransmitters and cytokines. Diagnosis of immune infertility begins by ruling out other known factors of infertility, including anatomic, tubal, endocrine, and genetic factors. Unexplained infertility Unexplained infertility occurs in 10-20% of infertile couples. The diagnosis of unexplained infertility satisfies at least the following criteria: normal semen analysis in the male partner, ovulation in the female partner, normal uterine cavity, and bilateral patency of both fallopian tubes under laparoscopy.