What Is Cervical Effacement?

What Is Cervical Effacement?

Last update: 15 February, 2018

When we are first-time mothers, anything scares us, especially when it comes to delivery. For example, hearing phrases like “cervical effacement” can be troublesome. Here’s what it means.

As the baby’s birth approaches, the mother’s body adapts. During gestation, the uterus acts as a protective capsule for the fetus.

The purpose is to preserve the pregnancy without letting go of any material. However, in the end the opposite occurs, as the baby must be born, or “let go” by the body.

Before the imminent delivery, the cervix goes through a process of gradual dilation. The slow cervical effacement or thinning can take hours. The cervix virtually disappears before delivery.

How does cervical effacement occur?

Cervical effacement is a normal process that occurs in preparation for the baby’s birth. A vaginal birth requires gradual dilation to guarantee a correct and safe delivery.

The cervix also begins to disappear at the end of pregnancy, even when a C-section delivery is planned.

In other words, as the moment of birth approaches, the cervix softens, shortens and thins to the point of disappearing. To mark the progress of cervical effacement, specialists categorize it by percentage.

To the son, the mother is a jewel. To the mother, the son is glory.

-Chinese proverb-

Depending on the proportion of the thinning, doctors can say that 30% or 50% has disappeared, all the way up to 100%.

When a 50% cervical effacement has occurred, for example, delivery is close. When 100% of the cervix has disappeared, childbirth is about to occur.

During the final weeks of pregnancy, your doctor will examine you to see how much of the cervix has disappeared. When delivery finally arrives, the examination will be performed more often.

What Is Cervical Effacement?

In first-time mothers, dilation occurs after effacement, but in women who have already given birth, the opposite occurs.

To find out if a woman is already in labor, specialists perform a vaginal palpation that allows them to assess the percentage of effacement. A disappearing cervix is a sign that strong uterine contractions have occurred. 

Usually the cervix is composed of a 3-centimeters-thick muscle that connects the vagina to the uterus. It will shorten until it blends with the uterus, causing the typical pear shape to be erased.

Phases of disappearance and dilation

First-time mothers may take longer to give birth because the dilation phase does not occur until after the cervix disappears. This process can be very slow and can sometimes take days.

However, when a woman has previously given birth, dilation and effacement happen at the same time.

Although all women are different, the natural way in which these phases occur is dilation, effacement and expulsion. As we have said, effacement can happen at the same time as dilation.

The goal is to go from a dilation of 0 centimeters to a dilation of 10 centimeters. 


Cervical effacement typically begins within about 72 hours of delivery, but sometimes begins within only 48 hours, as each woman is different.

At this stage, the cervix should have thinned to less than 1  centimeter. In other words, it has shortened by about 2.5 centimeters.


Once the effacement has occurred, dilation begins for first-time mothers. The small hole that is left begins to widen to fit the baby, and this is called dilation.

In each woman, the time it takes for this process can vary, but it always takes longer in first-time mothers. For example, in women who have given birth before, dilation occurs at a rate of 1.2 centimeters per hour, whereas the rate for new mothers is only 1 centimeter per hour.

All cited sources were thoroughly reviewed by our team to ensure their quality, reliability, currency, and validity. The bibliography of this article was considered reliable and of academic or scientific accuracy.

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This text is provided for informational purposes only and does not replace consultation with a professional. If in doubt, consult your specialist.