Cervical mucus

By BSc, MSc (embryologist), MD (gynecologist) and BA, MA (fertility counselor).
Last Update: 11/24/2014

The cervix is the lower part of the uterus and is projected inwards the vagina. It’s usually 3 – 4 centimeters long and its diameter is 2,5 cm. At the moment of birth it might increase up to 10 cm. One of the main advantages is that it’s usually a natural barrier against the entrance of bacteria.


The cervical mucus is a secretion inside the cervix that appears six days before ovulation.

Its apparition indicates the fertile days of the woman, and therefore, she can get pregnant. This is what produces that a woman feels humidity during her fertile days and dryness during her infertile days.

Variations through the cycle

The mucus has a viscous texture that gets less and less dense and increases in quantity as the days go by. It increases with the sexual hormones and has a great deal of importance in fertility, since it facilitates and enables the ascent of the spermatozoa. Any problem with it may constitute a problem with female fertility.

The cervical mucus disappears with ovulation, being replaced by dryness. The quality of the mucus is determined with the postcoital test (PCT). This test evaluates the state of the spermatozoa located in the mucus, if they are able to survive or not, and also the characteristics of the mucus.

Problems with the cervical mucus

There are several problems related with the cervical mucus that may be due to several causes and that may affect fertility directly:

  • Hormonal instability: for instance, the lack of estrogenic hormone alters the secretion of the cervical mucus.
  • Infections such as Chlamydia and gonorrhoeae.
  • Immunologic diseases: cause the apparition of antibodies in the mucus.
  • Lack of mucus: which can take place as a consequence of an operation such as conization, cauterization, cryosurgery...
  • Dysmucorrhea: alteration in the relationship mucus-semen.
  • Chronic cervicitis: presence of chronic vaginal discharge that may cause the apparition of leucocytes in the mucus.

Each woman’s cervical mucus is different. Even though it should vary depending on the stage of the menstrual cycle, this variations may not be so evident. Even in the same woman, every cycle is different and may secrete more or less quantity of mucus. Only in those cases where there’s a clear difference in more than one cycle, the gynaecologist must be consulted, so that he can check if this alteration is due to any infection or problem with the reproductive system.

When there’s trouble with it to the point that it prevents pregnancy, assisted reproduction techniques offer the possibility of intrauterine artificial insemination. This technique consists in the placement of the spermatozoa in the uterus, in order to avoid them to go through the cervical mucus.

FAQs from users

Can alterations in the cervical mucus lead to female infertility?

By Óscar Oviedo Moreno MD (gynecologist).

Yes, alterations in the cervical mucus can are a common cause of female infertility. The cervical mucus is a secretion produced before ovulation and it disappears after the woman ovulates. It has a sticky texture, and its mission is to pave the way for sperms toward the tubes. It is, in fact, a good indicator of female fertility.

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Authors and contributors

 Laura Gil Aliaga
Laura Gil Aliaga
BSc, MSc
Bachelor's Degree in Biology & Biochemistry from the Miguel Hernández University of Elche (UMH) and the University of Alicante (UA). Master's Degree in Biology of Human Assisted Reproduction. Embryologist at clinic UR Vistahermosa (Alicante, Spain). More information about Laura Gil Aliaga
 Óscar Oviedo Moreno
Óscar Oviedo Moreno
Bachelor's Degree in Medicine & Surgery from the University of Caldas (Colombia). Specialist in Internal Medicine by the Pontificia Universidad Javeriana of Bogotá. Degree standardized in Spain in 2003. Specialist in Gynecology & Obstetrics from the Complutense University of Madrid, with residence at Hospital Clínico Universitario San Carlos de Madrid. Expert in Reproductive Medicine and Certification in Obstetric-Gynecologic Ultrasound (levels I, II and III). More information about Óscar Oviedo Moreno
License: 282858310
Adapted into english by:
 Sandra Fernández
Sandra Fernández
Fertility Counselor
Bachelor of Arts in Translation and Interpreting (English, Spanish, Catalan, German) from the University of Valencia (UV) and Heriot-Watt University, Riccarton Campus (Edinburgh, UK). Postgraduate Course in Legal Translation from the University of Valencia. Specialist in Medical Translation, with several years of experience in the field of Assisted Reproduction. More information about Sandra Fernández

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