How Dilation and Effacement Work During Pregnancy


Dilation during pregnancy is your body's way of readying itself for the actual delivery of your baby. Not everyone woman's labor and delivery is the same, however, and women dilate differently.

Importance of Dilation During Pregnancy

Dilation occurs as your cervix begins to open and thin out prior to your baby being born. Of course, in the case of a scheduled Caesarian section, you may not have started to dilate. However, if you and your doctor plan on a vaginal delivery, your cervix will have to dilate in order for your baby to move out of your womb and through the birth canal.

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. Many women are disappointed when they are told they haven't begun dilating or they've only dilated one or two centimeters. Other women become very excited when they are told they've dilated three or four centimeters. However, it is important to understand that each of these scenarios may not necessarily predict when a baby will be born. In some cases, you may begin the dilation process and appear to get "stuck" along the way. It's easy to become anxious in those last few weeks before your newborn makes his or her arrival into the world, but if you do get stuck, don't worry--you won't be pregnant forever!

Dilation Facts

While your doctor may not be able to predict exactly when your labor will begin, he will want to keep track of what is happening with your cervix. Prior to dilation during pregnancy, the cervix remains thick, firm, and closed. It is a protective door that keeps your baby snug and secure within the womb. Several days or even weeks before your labor actually begins, your cervix will begin to thin out and start to open. Your doctor can check the size of the dilation by inserting his finger into your vagina and feeling the opening of the cervix. Keep the following points in mind:

  • Full dilation is 10 centimeters.
  • Dilation amounts can vary depending upon the size of the examiner's fingers.
  • Typically, a fingertip opening is referred to as one centimeter, but again, this can vary depending upon the size of the finger.
  • As the cervix opens, it also thins out. This is generally referred to as effacement and is usually measured in percentages, such as "50 percent effaced."
  • While the cervix must be dilated to 10 before delivery can take place, it should be 100 percent effaced as well.
  • Typically, the most difficult time of labor is during the "transition period", which usually occurs as a woman dilates between seven and 10 centimeters.
  • Depending upon your practitioner, you may be expected to dilate progressively once you are in the hospital.
  • Once a cervix is fully dilated and effaced, your cervix is often referred to as "ripe."

Common Questions

As the due date for your baby nears, you'll probably have lots of 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 Caesarian section.

The following are a few common questions women often ask regarding dilation:

  • I haven't begun to dilate, so will my labor be late?-Not necessarily. Dilation is often referred to as pre-labor since your body begins to ready itself for labor and delivery. This may just mean that once your labor does begin, it may take longer.
  • 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. Don't overdo it, however!
  • 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 ever feeling labor pains!

As always, if you have any questions or concerns regarding your pregnancy, please contact your physician..

How Dilation and Effacement Work During Pregnancy