Infertility due to cervical abnormalities is generally not taken seriously. Infertility caused by cervical abnormalities accounts for about 20% of infertility factors. As the first barrier for sperm passage, any anatomical and physiological changes in the cervix can affect the passage of sperm, resulting in abnormal cervical infertility. The main mechanisms of cervical infertility are anatomical abnormalities of the cervix and abnormalities of the cervical mucus. The following seven causes can lead to cervical infertility: Atresia and stenosis of the cervical canal Congenital atresia or stenosis of the cervical canal is mostly due to incomplete formation and fusion of the lower part of the bilateral Mullerian ducts. It is rare clinically and is often associated with uterine hypoplasia, and most of the secondary sexual characteristics are normally developed. Acquired atresia and stenosis of the cervical canal is most often seen after abortion or after electrocautery or cryotherapy for cervicitis. The main cause is inadequate dilatation of the cervix during aspiration or removal of the suction tube with negative pressure, resulting in damage to the endocervical lining and traumatic adhesions and atresia. Cervical canal dysplasia May be accompanied by uterine dysplasia. In severe dysplasia, the cervix is elongated. Abnormal position of the cervical canal is often associated with abnormal position of the uterine body. Chronic pelvic inflammatory disease or endometriosis can cause extreme posterior tilt, retroflexion or anterior flexion of the uterus, causing the ectocervix to be attached to the anterior fornix, resulting in shallowing of the posterior fornix and loss of the sperm storage pool, which is detrimental to the upward movement of sperm and leads to infertility. Cervical fibroids The main reason for infertility caused by cervical fibroids is the deformation and narrowing of the cervical canal, which affects the passage of sperm. Chronic cervicitis When the inflammation spreads to the pelvis through the uterosacral ligament, there may be pain in the sacral area, pelvic pain and dysmenorrhea, which is aggravated during menstruation, defecation or sexual intercourse. On examination, different degrees of erosion, hypertrophy and sometimes hardening of the cervix, polyps, lacerations, ectopia and glandular cysts can be seen. Inflammation can lead to the production of anti-sperm antibodies, which can cause infertility. Abnormal cervical mucus The glucose and other nutrients contained in the cervical mucus have a great impact on the survival and motility of sperm when crossing the cervix. Infertility is a major problem that plagues many families, and the causes vary, but care is essential to treat infertility. Infertility caused by the cervix is often overlooked, so it is important to be aware of this “invisible killer”.