How Dilation and Effacement Work During Pregnancy

Julie Kirk
Doctor examining belly of pregnant woman

Dilation and effacement of your cervix is necessary in order for you to have a vaginal birth. The duration of time it takes from being one centimeter dilated to being on the verge of delivering your baby can vary greatly from woman to woman.

Importance of Effacement and Dilation During Pregnancy

It is important to know what happens when effacement and dilation of the cervix occurs.

Effacement

When the baby's head drops lower in your pelvis, it will cause the cervix to stretch and thin out. This is known as effacement. This is also the time when you may pass your mucus plug. The doctor will describe how much you are effaced in percentages, which can range from 0% effaced which is no effacement whatsoever, to 100% effaced which is complete effacement.

Dilation

Dilation of the cervix is when the cervix actually opens. This will start to happen once the cervix begins to efface. The doctor will measure how much your cervix is dilated in centimeters. This will range from 0 to 10 centimeters. When the cervix is closed, it is measured at 0. When you cervix is completely dilated, your cervix will measure at 10 centimeters. Once you are at 10 centimeters, you can start to push to deliver your baby.

How Do Doctors Check for Dilation?

As you draw nearer to your delivery date, your prenatal check-ups will become more frequent. At some point, your doctor or nurse practitioner will begin checking your cervix to see if dilation has begun. A cervical check (or cervical exam) will include the following:

  • With a gloved hand, your doctor will evaluate the cervix by using one or two fingers to feel the cervical opening for dilation.
  • When two fingers are used, they are placed on each side of the cervical opening to estimate the distance between the fingers.
  • The dilation measurement is an estimation since the doctor is unable to visualize the cervix.
  • The cervical exams typically go smoothly, but it is not unusual to experience some discomfort during the exam.

Keep in mind that it is not possible to predict how long it will take until you are fully dilated. Every woman and every pregnancy is different. Some woman begin the dilation process and stop or "get stuck" along the way while others may dilate quite rapidly.

Dilation Facts

It is difficult for your doctor to predict exactly when your labor will begin or when your baby will be delivered. However, he will keep track of what is happening with your cervix.

The Cervix Before Dilation

Prior to dilation during pregnancy, the cervix will remain thick, firm, and closed. The cervix is crucial for keeping and holding the developing baby in the uterus until delivery.

Before and During Labor

Several days or even weeks before your labor actually begins, your cervix may begin to thin out and start to open. Your doctor will check if you're dilated by performing a cervical check to feel the opening of the cervix. Keep the following points in mind:

  • During active labor, your cervix will dilate from 4 to 7 centimeter.
  • During the transition period of labor, which is the most difficult part of labor, you will dilate from 8 to 10 centimeters.
  • If you are 100% effaced and completely dilated to 10 centimeters, this is when you will be able to push.
  • Women who have already delivered a baby, will typically dilate faster than first-time moms.
  • An epidural can slow down the dilation process.
Woman Giving Birth

Common Questions

As the due date for your baby nears, you'll probably have questions regarding the exact time of delivery for your baby. Dilation during pregnancy is just one indication that it won't be too much longer, but again, there isn't an exact science for predicting the birth of your child unless your doctor plans to induce your labor or perform a cesarian section.

Will My Labor Begin Later Since I Have not Started to Dilate?

Not necessarily. Dilation is often referred to as pre-labor since your body begins to ready itself for labor and delivery. Therefore, it is actually possible to have a closed cervix and deliver your baby with a matter of hours. While other women may stay put at 1 to 2 centimeters dilated for days, or even weeks.

Should I Exercise to Encourage My Cervix to Dilate?

Beginning a new exercise program in the last stages of your pregnancy is never a good idea unless you have spoken to your doctor first. However, unless your doctor has put you on bed rest, walking is a good exercise that may help your labor progress, but don't overdo it.

Pregnant woman walking in remote area

Is It Possible to Have Contractions and not Feel Them?

Yes, you may be surprised to learn that you have dilated three or more centimeters without even feeling labor pains.

Each Pregnancy Is Unique

With dilation and effacement of your cervix, there is no set timeline for how long it should take and when you can expect your baby to arrive. Every pregnancy is unique and somewhat unpredictable. As always, if you have any questions or concerns regarding dilation and effacement of your cervix or your pregnancy, in general, you should contact your doctor.

How Dilation and Effacement Work During Pregnancy