In plain language: Cervical (or pelvic) exams

You've probably heard of a cervical exam, maybe even had one. And "dilation" is a word almost everyone knows once they're pregnant. What's less talked about is that dilation is only one piece of what a cervical exam actually measures - and on its own, it can only tell you so much about where you are in labor.

Effacement and station are two additional pieces. Together, all three give a far more complete picture than dilation alone - of what your body is doing, and what might be worth asking about next.

What is cervical dilation?

Dilation is how open your cervix - the lower, narrow part of your uterus that connects to your vagina - is, measured in centimeters from 0 (closed) to 10 (fully dilated).

What is cervical effacement?

Effacement is how thin the tissue of your cervix is, measured as a percent. At 0%, your cervix is thick, and at 100% it’s paper-thin.

What is fetal station?

Station measures how far your baby has come down into your pelvis, on a scale from -5 (baby is high, not yet in the pelvis) to +5 (baby is crowning). A station of 0 means baby’s head has reached a fixed bony landmark in your pelvis called the ischial spines - sometimes referred to as “engaged.”

Why these numbers tell a more complete story together

Dilation, effacement, and station are three separate measurements of three separate things.

“6cm dilated" looks identical on paper, whether someone is also 90% effaced with baby at 0 station, or 40% effaced with baby still at -3. In practice, those are two very different points in labor.

This is important because labor isn’t always linear and your body doesn’t always move through these changes at the same time or the same pace. In my experience, it’s common for people giving birth the first time to efface faster than they dilate, and dilate faster than baby descends. That could look like an exam where someone is 4cm dilated, 80% effaced, and -3 station. Reading these numbers together takes some practice, and is something your doula can help with.

What these numbers don’t tell us

Dilation, effacement, and station tell us where your body is now, but not where it will be in 2 or 4 hours. They don’t say anything about how baby is doing, how you're coping, or how much longer things will take. Some dilation before labor starts (a 1cm check at a prenatal appointment, for example) doesn't reliably predict when labor will begin. You can also be fully dilated (10cm) with baby still high in your pelvis, which can mean more time ahead - waiting, pushing, or both.

How a doula can help

Your doula can help remind you what these numbers mean, so you don’t have to hold on to all this information while doing the work of being in labor. Station in particular tends to shape what we try next - positions that open your pelvic inlet (a supported squat, side-lying with a peanut ball) when baby's still high, and ones that open the outlet (hands-and-knees, a deep lunge) once baby's descended. Sitting backwards on the toilet can be a good position, since your pelvic floor relaxes there without you trying.

Explore this further

March of Dimes: Stages of Labor - a plain-language overview of what typically happens at each stage

Evidence Based Birth: Evidence on Prenatal Checks at the End of Pregnancy - includes evidence on the benefits and risks of cervical exams at the end of pregnancy, and advice on how to decline one

Cleveland Clinic: What is a Cervical Check - an explanation of cervical checks, what providers are checking for, and what you can expect during one