The cervical factor is almost exclusively associated with the quality of cervical mucus and its interaction with the sperm. Cervical mucus is secreted by glands found in and around cervix. Hormonal changes throughout a woman’s reproductive cycle change the amount and consistency of this mucus.

Its role is to nourish and help transport sperm through the cervix into the uterus. It is also a clue that ovulation is coming.

In some women, there are sperm antibodies in the mucus of the cervix. These create agglutinations and the sperm cannot reach the uterine cavity, even in the ovulation phase (fertile days). The hostility of cervical mucus is the main cause of infertility in 9-15% of couples.

The main way of testing the mucus is the postcoital test (PCT), but this test is very controversial. Its effectiveness is disappointing in clinical practice and its predictive value is considered by many to be limited. Typically, positive PCT indicates the presence of a sufficient number of mobile sperm in mucus 4-10 hours after contact, and negative PCT shows the absence of sperm. Practically, if more than 50 sperm with progressive motility per field of vision is found in PCT, in the mucus, 9-24 hours after contact, male factor can be excluded as cause of infertility.