The cervix is connected to the top of the vagina and the cervical canal contains many glands that secrete alkaline mucus that facilitates sperm movement. Under the influence of certain factors, the nature of the cervical mucus can change, which makes it difficult for sperm to pass through the cervix. According to statistics, infertility due to cervical causes accounts for 3-5% of female infertility. Why does abnormal cervical mucus cause infertility? 1. Ovarian dysfunction: women may have symptoms such as ovarian non-ovulation, luteal insufficiency and hyperprolactinemia. Because the ovaries cannot ovulate normally or there is no estrogen peak before ovulation, the amount of cervical mucus secretion cannot increase correspondingly in the middle of menstruation, or the cervical mucus cannot undergo physical and chemical property changes that are conducive to sperm passage. 2, excessive use of anti-estrogen drugs: such as the use of clomiphene to promote ovulation, triamcinolone for breast diseases, etc. can cause cervical mucus in women. 3, damage to the cervical canal: including partial hysterectomy, electrocautery of the cervix, multiple scrapings, etc. can affect women’s fertility. 4, cervical inflammation: If the cervix is infected by pathogens, the cervical epithelium loses its response to estrogen, and it is difficult to secrete normal cervical mucus even if the ovaries are functioning normally. 5.Destruction of uterus and cervical immune function: In the uterine cavity and cervical canal, if there are substances that inhibit sperm activity or damage sperm, such as secretory anti-sperm antibodies and tumor necrosis factor A, it will cause infertility.