Infertility is a common and frequent disease in obstetrics and gynecology. Statistics show that about 10 out of 100 married couples suffer from infertility. What is infertility? A person who has a normal sex life without contraception and is infertile for one year is called infertile. Those who have never conceived are called primary infertility and those who have conceived in the past are called secondary infertility. In order to better understand why infertility occurs, let’s first describe what conditions must be present for conception to occur under normal circumstances. Basically, there are 3 elements that need to be present: ① Normal and high quality “seeds”: refers to the man’s testicles can produce normal sperms, and the woman’s ovaries can discharge healthy and mature eggs. The road should be smooth: the sperm produced by the testes is stored in the epididymis and discharged through the vas deferens, ejaculatory ducts and urethra during ejaculation, and the above pipes must be smooth for the sperm produced by the testes to be discharged. The female reproductive tract must also be smooth, the umbilical end of the fallopian tube can normally pick up the ovary discharged eggs, so that normal sexual intercourse can enter the vagina sperm can be unimpeded through the cervix, the uterine cavity to reach the fallopian tube, and the egg to meet the fertilization. The fertilized egg can also pass through the fallopian tube into the uterine cavity. ③”Fertile soil” is suitable for the fertilized egg bed “germination”: after fertilization of the egg, the development of the uterus while moving in the direction of the uterus, 3-4 days after the arrival of the uterine cavity, 6-8 days into the nutrient-rich uterine lining, and then continue to develop into a fetus. Fertilized egg development and endometrial growth is synchronized, such as fertilized egg early or delayed entry into the uterine cavity, the endometrium will not be suitable for fertilized egg bed and “germination”, it is impossible to get pregnant. One of these conditions is essential for conception. What are the common causes of infertility? Factors affecting conception can be on the woman’s side, the man’s side, or on both sides. Women’s factors account for 60%, men’s factors account for 30%, and both men’s and women’s factors account for 10%, while a very small proportion of infertility is unexplained, meaning that the cause of infertility cannot be identified at the current level of medical development. 1, the causes of women: ① “seed” production and discharge abnormalities: such as anovulatory menstrual irregularities, ovarian lesions such as congenital ovarian developmental anomalies, polycystic ovary syndrome, premature ovarian failure, functional ovarian tumors, and adrenal gland and thyroid function abnormalities affecting the ovary function leading to ovulation and so on. ② “road” is not smooth: abnormal development of the vulva and vagina, inflammation, scarring and so on, causing difficulties in sexual intercourse or sperm can not enter the vagina, or enter the vagina sperm can not further pass forward through the uterine cavity to reach the fallopian tube and the egg will meet; tubal obstruction or tubal impermeability, such as chronic inflammation of the fallopian tubes, tuberculosis, endometriosis leads to Tubal blockage caused by pelvic adhesions and so on. Among them, tubal factor is the more common cause of female infertility. ③ “soil” is not fertile, not suitable for fertilized eggs to germinate: such as uterine congenital dysplasia, uterine malformation, endometrial hyperplasia, endometrial inflammation, submucosal leiomyoma, endometrial tuberculosis, endometrial polyps, and endometriosis, etc. may affect the fertilized eggs to germinate, resulting in infertility. 2, male causes: ① “seed” abnormal: mainly due to congenital or acquired causes of semen abnormalities, manifested as oligospermia, azoospermia, weak spermatozoa, sperm development stagnation, high rate of malformed spermatozoa or semen liquefaction incomplete. ② sperm “road” is not smooth: vas deferens abnormalities mainly caused by semen abnormalities, external genital dysgenesis or impotence, premature ejaculation, ejaculation, retrograde ejaculation, etc. can make the sperm can not be normally discharged into the vagina. Immune factors: under the condition that the immune barrier of male reproductive tract is destroyed, sperm and sperm plasma produce antibodies against their own sperm in the body, that is, anti-sperm antibodies, so that the ejaculated semen produces its own agglutination and can’t pass through the cervical mucus. 3, both men and women factors: ① lack of basic knowledge of sexual life: such as in the clinic, seen three years of marriage and infertility patients, the woman in the gynecological examination, found that the hymen is still intact; in the ovulation period (ovulation 2-3 to 24 hours after ovulation) to have normal sex in order to conceive, and so on. ② men and women looking forward to pregnancy caused by mental overstress: often see some infertile couples, seek medical treatment, failed to get pregnant, carry a child, mental relaxation, even pregnant with their own children. ③ immune factors: such as anti-sperm antibodies and anti-Zona pellucida antibodies produced in the woman’s body can cause sperm and egg can not be combined or sperm can not penetrate the egg, affecting conception.