Updated June 1,2018
It takes a long time for the cervix to dilate 5 centimeters. It’s going to be many days or weeks of having Braxton Hicks contractions before labor begins just to get the cervix ready for labor. But if the cervix isn’t “ripe” for labor and your water breaks or your contractions start, then it’s going to take many hours of early labor just to soften and efface the cervix. When I say many hours, it could be 12-24 hours of having light, but persistent contractions just to get to 2-3 centimeters dilated. And then it will be a few more hours to dilate to 4-5 centimeters.
Before the cervix can dilate or open up, it must first soften. This thinning and softening of the cervix is called effacement, which is measured in percentages. Usually, the cervix is long, hard and closed. As a pregnant woman has Braxton Hicks contractions during pregnancy or in labor, the cervix starts this effacement process which ripens the cervix and prepares it for labor. As the cervix continues to soften, it starts to dilate as well.
You may be checked by your doctor or midwife as your due date approaches and found to be 50% effaced and a fingertip dilated. The next week you may be 60% effaced and still a fingertip dilated. The next week, your cervix may be 2 centimeters dilated. The effacing and dilating of the cervix can take many weeks before “real labor” begins. The more contractions you have before labor starts, the shorter your labor will be.
If you slowly dilate during the last weeks of pregnancy, then your cervix will be “ripe” and ready for labor. You may dilate to 5 centimeters after just a few short hours of labor. And if this isn’t your first baby, getting to 5 centimeters could happen very quickly.
However, there is another scenario. If your labor starts and your cervix hasn’t already done a lot of the effacing and dilating that I just described, it will take many hours of light contractions just to get to 2-3 centimeters dilated.
Sometimes, your water may break before contractions begin. You might stay home for about 12 hours having light contractions. During this time, you can follow your normal routine. Eat when you’re hungry, drink when you’re thirsty. You can even relax in the bath after your water breaks if you want to. After 12 hours of these light contractions, your cervix may only be dilated 1 centimeter. It may be another 12 hours or more before the cervix is dilated to 4-5 centimeters and active labor kicks in.
So be prepared for a long, slow early labor if your cervix hasn’t softened during pregnancy. So to answer the question, how long does it take the cervix to dilate to 5 centimeters? A long time.