Dilation in Late Pregnancy

Dilated in Late Pregnancy

Expectant mother in hospital labour ward
Peter Dazeley/Photographer's Choice RF/Getty Images

One of the questions I'm often asked about late pregnancy is about dilation, the opening of the cervix. People ask me questions like: "What does it mean that I'm 1 cm dilated at 36 weeks?"

What does it mean to be dilated?

Being dilated means that your cervix has started to open in preparation for the birth of your baby. Your cervix must go from not dilated to 10 centimeters dilated before your baby can be born. While many of us this of this as a process of labor, many women will be dilated, even if just slightly, prior to the beginning of labor.

Effacement or being effaced is about the thinness of your cervix. During your pregnancy your cervix is roughly three-five centimeters long. Effacement is a measure of how thin it is and is measured in percentages. So a cervix that is not effaced is 0%, half effaced is 50% and completely effaced is 100% effaced.

How do I know if I'm dilated?

Being dilated in late pregnancy is something that you would find out in a vaginal exam. Many women will have a vaginal exam between the 35th and 37th weeks of pregnancy as a part of the group B strep (GBS) screening. Your midwife or doctor might casually tell you that you are a bit dilated and/or effaced.

"I was really excited that my doctor told me I was already starting to dilate," laughs Clare. "I was talking on the phone to my mother when the nurse overheard me telling her how excited I was, sure that meant the baby would be here soon. I was 38 weeks pregnant after all! The nurse laughed and told me it could be tonight, or in a month. I went all the way to just over 41 weeks, being a bit more dilated every week. It was total hype. I'm not finding out next time."

What does it matter if I am dilated before labor?

The big question that you may have about being dilated is whether or not that means that your baby is likely to be born soon. While being dilated is certainly a positive step towards labor, in and of itself it is not a sign of labor or even that labor is coming in a certain amount of time. In the absence of contractions, being dilated is just preparing for labor.

Think about it this way, if you are 36 weeks pregnant and your practitioner finds that your cervix is 1 centimeter dilated - that means your cervix is open the width of approximately a Cheerio. This does not mean that your baby's birth is impending, but it is one less centimeter than you have to do in labor.

So sit back and relax as much as you can while you wait for the real signs of labor.

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