The cervix or cervical factor is found as a cause of infertility in up to 5% of infertility cases.

Cervical stenosis or poor cervical mucus and sperm interaction can interfere with sperm entering the uterus. After sexual intercourse the cervix provides sperm transport up through the reproductive tract.

Cervical mucus production and characteristics vary depending on the saturation of oestrogen in the late follicular phase.

At the beginning of the menstrual cycle, there is a little cervical mucus and the consistency is viscous. Towards the middle of the cycle oestrogen saturation in the mucus increases, it is richly formed and becomes stringy. Mucus production reaches the maximum 24-48 hours before ovulation. Mucus can be stretched between the fingers into 5-7 cm length and resembles egg whites. Mid-cycle a crystalline structure is formed in the mucus; it consists of countless micro-channels through which the sperm can move more easily. Further, these micro-channels act as a filter that stops abnormal sperm.

Cervical mucus secretion during the cycle is affected not only by hormonal fluctuations but also various medications. Other hypoestrogenic conditions (when the ovaries produce too little oestrogen) reduce the formation of mucus, which impedes the sperm from entering the uterine cavity.

Stenosis can be:

Congenital – congenital isolated cervix or a combination of the uterus and cervix;

Obtained – after surgical procedures, infections, prolonged hypoestrogenic condition, or radiotherapy.