Cervical Dilation Meaning and Symptoms

What does it mean for your cervix to dilate and efface, and can you tell it's happening? We broke down what cervical dilation is, and what signs to look for.

pregnant woman at doctor
Photo: S_L/Shutterstock

Have you ever wondered what it actually means for your cervix to dilate? Cervical dilation and effacement are terms that doctors use to describe the process of labor starting to progress to the point of birth. But even if you've heard the terms, you may not actually understand what the process entails.

First things first: the cervix is a cylinder-shaped tissue at the bottom of the uterus that connects the uterus to the vagina. The cervix acts like a "door "to the uterus, and it's covered by a plug of mucus to protect the baby. In preparation for delivery, the cervix thins out (effacement) and opens up (dilation) to allow the baby to pass through the birth canal.

Keep reading to learn more about cervix dilation and effacement, and how to check whether it's happening to you.

What is Cervical Effacement?

Cervical effacement happens when your cervix thins and stretches to prepare for vaginal delivery. It's caused by the baby's head dropping into the pelvis and pressing against the tissue. Doctors track cervical effacement through percentages: A cervix that is 100% effaced has gone from the shape of a thick-walled cone to that of a flat, thin cup beneath the baby's head.

If you're 50% effaced, that means you're halfway there, says Laura Riley, M.D., medical director of labor and delivery at Massachusetts General Hospital, in Boston. Some people, especially those who have given birth before, may have some degree of cervical dilation and/or effacement well before their due date, but you will cervical changes in order to be considered "in labor."

In other words, even if your doctor tells you that you're dilated, it's not until you become more dilated or more effaced that it means labor could be starting.

What is Cervical Dilation?

Dilation is characterized by an opening of the cervix, which helps the baby pass through the birth canal. There's no set time frame for dilation; it can start weeks, days, or hours before labor. Your contractions will gradually open your cervix to that magical dilation measurement of 10 centimeters.

When your cervix has dilated to that point (about the width of your hand) and your baby's head has descended far enough down, your midwife or obstetrician will tell you that it's time to push and deliver your baby.

3 Cervix Dilation Symptoms

Can you feel your cervix dilating? Usually not, says Ashley Brichter, founder and CEO of Birth Smarter, which offers in-person and virtual childbirth classes for expectant parents.

However, there may be other signs that your cervix is dilating (or getting closer to dilation). Here are a few things to look for:

1. You lose your mucus plug

During pregnancy, a glob of mucus seals the cervical opening shut, and it protects your baby from outside germs and bacteria. As effacement and dilation progress, you may notice your mucus plug pass through the vagina. The mucus plug usually looks like a thick, gelatinous, yellowish-white substance, and it can also be tinged with blood.

2. You have bloody show

As delivery nears, the blood vessels in the cervix capillaries will rupture, tinting your vaginal mucus with blood. You might notice this blood-tinged discharge when you use the bathroom, wipe, or even as discharge in your underwear.

While you'll always want to check with your doctor if you have bleeding during pregnancy, a small amount of blood show can mean that labor will start sooner rather than later!

3. You are experiencing some pelvic discomfort

Women may feel a small pressure from cervical dilation and effacement, says Brichter. However, cervix dilation pain is extremely rare.

How to Check Cervix Dilation

It's pretty difficult to check your cervical dilation on your own, so you can ask your doctor if you are dilated at your prenatal check-up or if you're having contractions and you head to the hospital. Your doctor or nurse will insert their fingers (with sterile gloves on, of course) into your vagina to manually check if your cervix is open and thinning out.

But even if your cervix has started to thin and open, when you'll actually go into the active labor phase is still a mystery.

In general, though, once active labor begins, the average progress is about 1 centimeter dilation per hour for your first baby and 1.5 centimeters per hour for a second baby, according to Dr. Riley. The good news is, especially for first-time parents, the first phase of labor can take some time, but once you've started dilating, it means you're well on your way to welcoming your baby.

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