Functions of the Cervix in Reproductive Health

The cervix is the lower third portion of the uterus. It forms the neck of the uterus and opens into the vagina (which is also called the endocervical canal).

The cervix is a little over an inch long and just about an inch wide. Made up largely of muscle tissue, it plays a minor role except during pregnancy or if a medical problem emerges.

Because of its location between the uterus and the vagina, the cervix is rarely seen. Seeing your own cervix requires a mirror and bright light.

It's possible to feel the cervix with your finger; if you do so you'll notice that it changes texture over the course of your cycle.

Doctor is checking a patient
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The narrow opening of the cervix is called the os. The cervical os allows menstrual blood to flow out from the vagina during menstruation.

The cervix is covered by the epithelium, which is made of a thin layer of cells. Epithelial cells are either squamous or columnar (also called glandular cells). Squamous cells are flat and scaly, while columnar cells are, as their name suggests, column-like.

There are three parts of the cervix:

  1. The lowest part, which can be seen from inside the vagina, is called the ectocervix. The center of the ectocervix can open, creating a passage between the uterus and vagina.
  2. The highest part is the endocervix, also called the endocervical canal. It's the passage between the ectocervix and the uterus.
  3. The point in the middle where the endocervix and ectocervix meet is called the transformation zone.


The cervix produces cervical mucus. Cervical mucus changes in consistency over the course of your menstrual cycle. At the point of greatest fertility, the cervix produces a good deal of clear mucus which helps to promote pregnancy.

During pregnancy, the mucus produced by the cervix thickens to create a cervical "plug." This shields the growing embryo from infection. The cervical plug thins and is expelled when birth is imminent.

During menstruation, the cervix opens a small amount to permit the passage of menstrual flow. During pregnancy, the cervical os closes to help keep the fetus in the uterus until birth.

Another important function of the cervix occurs during labor when the cervix dilates (widens), to allow the passage of the fetus from the uterus to the vagina.

Conditions and Problems

A number of issues can affect the cervix. These include:

The cervix can cause issues during pregnancy and birth, as well. For example, cervical insufficiency occurs when the cervix is too weak to maintain a pregnancy.

Having regular Pap smears is imperative to detect early changes to the cervical cells that may lead to cervical cancer. However, the majority of abnormal Pap smears are due to inflammation or infection.

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Article Sources
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  1. American Cancer Society. What is cervical cancer? Updated January 3, 2020.

  2. Canadian Cancer Society. The cervix.

  3. Cleveland Clinic. Incompetent cervix. Updated October 9, 2019.

  4. National Institutes of Health, National Cancer Institute. Understanding cervical changes- A health guide for women. Published May 2017.

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