Most women know that the words effacement and dilation are music to their ears while in labor. The bigger the number or percentage, the closer she is to delivery. Your goal is to be 100% effaced and 10 centimeters dilated. But what exactly does it mean to be “90% effaced” or “5 centimeters dilated”?
Both effacement and dilation are terms that refer to your cervix. Think of your cervix as a doughnut located at the top of your vagina. (If you have ever seen a photo of an actual cervix, it really does look like a doughnut or a swim tube.) Effacement describes the process of the doughnut becoming thinned out and flattened. Dilation is the process of the center of the doughnut stretching out to become wider and wider.
As the baby’s head presses down on the cervix, the cervix is compressed and begins to efface. Think of pulling a turtle neck over your head. Before you put on the shirt, the collar is long and narrow. Effacement has to do with the shortening of the cervix. The farther you pull the turtle neck over your head, the less collar is left over your head. This is effacement. Now imagine the turtle neck is completely on your head, but not quite to your neck. Your face is squashed inside the collar. There is no longer any length left above the crown of your head. This is 100% effaced.
Dilation is closely tied to effacement and it happens at the same time. Think about the edge of the turtle neck collar and how stretched out it is. When you pull the turtle neck over your head, there comes a point when the collar does not need to be stretched any more because it’s around the largest part of your head – your face. This is complete dilation. The only difference is the baby’s head does not have to be completely in the middle of the cervix for it to be fully dilated because your contractions are what is opening the cervix. The cervix does have to be completely dilated for the baby to pass through however.
If your cervix looks like a doughnut, then once you are completely effaced and dilated, the doughnut disappears. When your doctor or nurse checks to see your progress, the cervix will be almost completely undetectable except for a very thin rim around the baby’s head. I still remember the nurse exclaiming in surprise, “honey, your cervix is gone!” If I hadn’t understood what she meant, I might have panicked!
One important thing to remember is the number of centimeters or the percentage is just an estimate. The doctor or nurse inserts two fingers and then opens them to feel how open the cervix is. Depending on the size of their hands, they may give a larger or smaller estimate. The first time I got checked, the nurse estimated 3-4 centimeters. When my doctor checked later on, he only measured 2 centimeters. It’s not that my cervix closed, but that the nurse and the doctor had two different ideas of what a centimeter feels like! Try not to worry too much about the number. The only important thing is that you are making progress to delivery. It helps if you have the same person checking you each time.