When your cervix is effaced in pregnancy, it means that it is thinner and shorter than its previous condition. During the process of effacement your cervix gradually goes from thick and long to thin and short until it becomes indistinguishable from the body of your uterus.
Onset and Progression
As you get closer to your due date, your cervix may gradually efface as part of the normal progression towards labor and delivery. The process usually starts spontaneously and, like cervical dilation, effacement is necessary for vaginal delivery of your baby.
Gradual thinning and shortening of your cervix can start a few weeks or days before your due date. This effacement may not start, however, until hours or minutes before the onset of true labor, or it may start during labor. If you have Braxton-Hicks or pre-labor contractions before your labor, your cervix might efface during that time.
You cannot predict how quickly your cervix will efface before or during labor, but the following factors may apply:
- If this is your first baby expect that effacement and labor will progress more slowly.
- If your cervix began to efface or soften before labor, effacement and labor may progress quicker.
- It is likely genetic factors may play a role.
Checking for Effacement
Your doctor or midwife might check to see if your cervix is effacing during pregnancy pre-term or near term to make decisions about labor and delivery. During labor he checks to see if you are making progress.
Near or after term, your doctor or midwife might check your cervix for effacement to see if you might go into spontaneous labor soon. Cervical effacement is also one measurement used in the Bishop score to pre-evaluate you for the possibility of artificial induction of labor.
According to the American Journal of Obstetrics and Gynecology, the more effaced your cervix at the beginning of labor the quicker it will dilate and the shorter your labor and delivery will be.
Your doctor might check your cervix for premature effacement and dilation if you have symptoms and signs of pre-term labor before 37 weeks of pregnancy. This might help predict the likelihood of a premature labor and delivery or feasibility of having a delivering vaginally if it is necessary to induce labor.
During the first stage of labor, along with other criteria for gauging the progress of labor, your doctor or midwife checks your cervix for progressive effacement. When your cervix becomes fully effaced, if it is also fully dilated, you are at the end of the first stage of labor and ready to push.
Your doctor or midwife assesses effacement with two fingers in your vagina. He checks how firm or thin your cervix is and checks the length from the end of your cervix to where it meets your uterus at the top of your vagina. This is not a precise measurement; however, to your doctor or midwife the important questions to answer are:
- Is your cervix uneffaced?
- Is your cervix starting to efface?
- Is your cervix progressively effacing during pregnancy or labor?
- Is your cervix fully effaced?
Unit of Measure
Effacement during pregnancy is usually noted as percent of your usual length. For example when your cervix is your usual length it is 0% effaced. When it is half of its pre-effacement length it is said to be 50% effaced, and it is 100% or fully effaced when no cervix can be felt.
Cervical effacement helps your cervix dilate easier and prepares you for vaginal delivery of your baby. It usually starts spontaneously as part of the normal course of pregnancy, labor and delivery though you can't predict its onset and progression.