Cervical Factor Infertility can occur when the mucus lining the cervix is too thick, therefore impeding the man’s sperm from progressing past the cervix. It can also occur when a woman produces antibodies that attack and kill the sperm before it can enter the cervix. Intrauterine insemination (IUI) is often the first line treatment for cervical factor infertility.  

The cervix is the opening between the vagina and the uterus and it is lined with numerous small glands (cervical glands) which produce mucus. Once sperm are ejaculated they swim through this mucus from the vagina through the cervix and into the uterus. The mucus also provides nourishment for the sperm.  If the cervical mucus is inadequate, the sperm cannot reach and fertilise the egg.

Estrogen stimulates the production of cervical mucus and low levels of this hormone can lead to diminished or thickened cervical mucus which inhibits sperm transport.   Sometimes progesterone is given to try and improve mucus quality. Drugs that lower estrogen levels, such as Clomid, can negatively affect the cervical mucus. 

The post coital (after intercourse) test is used to determine the ability of sperm to survive in the cervical mucus.  A sample of the mucus is obtained after intercourse and examined under a microscope.  If numerous dead or immobile sperm are seen it indicates a possible antigen/antibody reaction. This occurs when the female’s immune system mistakes sperm for pathogens (invading bacteria, allergic factor, virus, etc.) and seeks to destroy them. In some cases, the male may produce antibodies to his own sperm.

When cervical factor infertility is diagnosed the first line treatment is usually intrauterine insemination (IUI). In an IUI cycle, the sperm are collected, concentrated, washed and specially prepared, and inserted directly into the uterus using a small catheter. Unwashed sperm can cause very serious allergic reactions and should never be placed in the uterus. IUI bypasses the cervical mucus insuring that the sperm reach the uterus. 

If three cycles of stimulated IUI fail, in vitro fertilisation is usually the next treatment option.