By Cristina Mestre Ferrer BSc, MSc (embryologist).
Last Update: 03/07/2016

The uterine cervix or cervix is the lower part of the uterus, thanks to which the vagina is connected to the uterine cavity.

Its function is basically acting as a barrier to sperm penetration on their way towards fertilizing the egg. It is also the path through which menstrual bleeding exits the body.

Between 5 and 10% of couples experiencing some type of infertility are diagnosed with what is known as cervical factor infertility.

Cervical factor is a leading cause of female infertility when there exist anatomical and/or functional abnormalities in the cervix. These alterations interfere with the adequate migration of spermatozoa towards the uterus and the Fallopian tubes in their attempt to reach the egg.

Cervical mucus

The cervix or cervix uteri secretes a thick mucus known as cervical mucus or vaginal discharge, which consistency and appearance varies depending on the phase of the menstrual cycle the woman finds herself at the moment, due to hormonal action.

The following are the main functions of the cervical mucus:

  • Allowing the passage of sperm while the woman is ovulating
  • Protecting the sperm from the vagina and its environment
  • Selecting the healthiest spermatozoa by leaving behind those without fertilizing potential

Under the influence of estrogens—about halfway through the menstrual cycle—, vaginal discharge acquires a watery appearance, and is usually present in abundance. This allows sperm penetration and paves the way for sperm to reach the egg. Conversely, it gets thicker, viscous, and less abundant after ovulation, which is to say, when progesterone release begins.

Cervical abnormalities

A woman may experience cervical abnormalities at two levels: on the one hand, functional abnormalities and, on the other, anatomical abnormalities.

    Functional cervical abnormalities

Mucus features such as consistency, amount, etc. may hinder the right functioning of the cervix. This may block the entrance of sperm into the uterine cavity and therefore lead to female infertility.

As an example, women whose estrogen release during ovulation is insufficient tend to produce thicker vaginal discharge than usual during these days, therefore making it difficult for sperm to enter the uterus.

The consumption of certain medicines, infections, the presence of anti-sperm antibodies, and severe hormonal imbalances or endocrine disorders are the main causes as to why vaginal discharge may vary its qualities and work differently.

    Anatomical cervical abnormalities

Obstructive processes such as polyps, cysts, etc. are included as well as temporary or surgical trauma that cause tears, fistulas, or incontinence of the woman’s internal and external orifices, with the subsequent functional alteration of the same one.

On the other hand, cervicitis or inflammation of the cervix, whether it is acute or chronic, may lead to female infertility as well. It is commonly caused by microbial infections such as chlamydia, Trichomonas vaginalis, candida infection, or mycoplasma.

Acute cervicitis is a common inflammation during the puerperal period. Cervical stenosis, agenesis, and bicervical uterus are also frequent cervical anatomical alterations that may lead to fertility problems among women.

Diagnostic tests

The main diagnostic tests carried out to determine the presence of cervical factor infertility are:

  • The postcoital test (PCT): it is used to assess the presence or absence of motile sperm in the woman’s vaginal discharge after having had sexual intercourse.
  • In vitro immunological tests: apart from evaluating the characteristics of the cervical mucus and the seminal fluid, the presence of anti-sperm antibodies is also studied in both substances, as well as the spermatozoa potential to penetrate the cervical mucus.

Both diagnostic tests allow the specialist to examine the characteristics of a woman’s cervical mucus in order to determine whether the passage of sperm is possible or something is blocking it.

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Authors and contributors

 Cristina Mestre Ferrer
BSc, MSc
Embryologist
Bachelor's Degree in Biological Sciences, Genetics & Human Reproduction from the University of Valencia (UV). Master's Degree in Biotechnology of Human Assisted Reproduction from the UV and the Valencian Infertility Institute (IVI). Embryologist at IVI Barcelona. More information
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2 comments

    1. margaret mcewan

      How could I improve the quality of my vaginal discharge? In my case, I produce too many anti-sperm antibodies, so it literally kills sperm.

      • Sandra FernándezBA, MA

        Dear margaret,

        Firstly, let me explain you what are the characteristics you should look for in your vaginal discharge in order to determine whether you produce fertile cervical mucus or not:

        1. Thick and watery consistency or stretchiness
        2. Clear color, either a white or yellow tint
        3. pH above 7
        4. Possibly sweeter scent

        To improve consistency, the most important thing to do is staying hydrated, just like should be done for improving your lips and skin. There are some herbal remedies like taking evening primrose oil, but there is no scientific proof that they actually work.

        As for improving cervical mucus quality, the main thing to keep in mind is following an overall healthy TTC diet. By doing this, women usually get their body functioning as best it can as a whole. For instance, avoiding foods containing too much sugar, as well as processed foods, would be a good start.