Understanding Terms: Effacement and Dilation
Imagine this: you cheerily show up to your 37 week OB appointment to listen to your baby’s heartbeat and talk to your doctor about your preparations for labor and delivery. Your doctor asks if you’d like him or her to perform a cervical exam to see if your cervix has started becoming favorable for delivery, and you say “sure, why not!” Your doctor carefully performs the exam with a gloved hand and says casually, “you’re about two centimeters dilated and 50% effaced.” You’re taken aback, “two centimeters?!” you think, frantically. You hadn’t been having any more than some light cramping, does this mean you’re progressing in labor? Do you need to get to the hospital? You get back into your car and quickly Google “cervical dilation” and learn that your cervix needs to dilate to ten centimeters before delivery. Then, you text your friend who tells you her water broke at one centimeter; another friend tells you she was at three centimeters for three whole weeks! All of this information is overwhelming and you’re not sure what it means or how to interpret it, but now you’re feeling even more anxious about what your body is doing to prepare for the birth of your baby.
There are a few terms that are important to understand as a person in labor (or a support person!), and “effacement” and “dilation” are both equally important ways that your body prepares for the birth of your baby. Effacement and dilation of the cervix are two observable and measurable factors that are important for a successful spontaneous vaginal birth. Attaining a basic knowledge and understanding of these terms and how the cervix works during labor can help you better understand what your body does in preparation for delivery, as well as ease any anxieties you may feel after learning the effacement and dilation of your own cervix as you attend your last few doctors visits leading up to your due date.
The Cervix During Pregnancy
Your cervix is a tube-shaped structure that sits between your vagina and your uterus. During pregnancy, your cervix lengthens and forms a mucus plug, two protective measures to keep harmful bacteria from entering the space where the fetus is growing in the womb. The cervical opening looks a bit like a donut, with the ability to open and become either soft or firm at different times of your menstrual cycle, but during pregnancy, the opening is tightly closed and firm. When the baby is ready to be born, there is an intricate and spontaneous signaling of hormones that happens between the placenta and the fetus, causing uterine contractions that allow the cervix to soften, become shorter in length, and open to allow the passage of the baby through the birth canal.
What does “effacement” mean?
Effacement refers to the softening, shortening and thinning of the cervix, caused by uterine contractions. Many women may not even realize they’re having contractions that are productively changing their cervix, oftentimes they might experience some light cramping or other sensations that could be chalked up to normal third trimester discomfort. Some may feel like the baby has “dropped” as a result of resting lower in the pelvis due to the cervix becoming shorter and thinner. Cervical effacement is calculated by birth professionals using a percentage. During a cervical exam, your doctor or midwife will estimate effacement based on how the cervix feels. Effacement and dilation work together to bring the baby down and out, but it is important to understand that effacement also has a role in the labor process, not just dilation! Your cervix cannot dilate successfully if your cervix is not becoming thinner and softer.
What does “dilation” mean?
Dilation refers to the opening of the cervix, caused by uterine contractions and aided by cervical effacement. As the cervix thins, the cervical opening becomes wider to allow for the passage of the baby. Just like effacement, it’s possible for your cervix to dilate a couple of centimeters in the weeks leading up to birth. As a result, some women may experience release of some or all of their mucus plug, or “bloody show”. Some women may not realize they’ve dilated at all until a doctor of midwife performs a cervical exam. It is normal to dilate before “realizing” you’re having contractions, but dilation of the cervix, along with effacement, is a good indication that your body is gearing up for true labor and delivery. A fully dilated cervix is open to ten centimeters, and it’s not possible to fully dilate without being fully effaced!
Dilation and effacement are valid indicators that your body is in the process of preparing for birth, but knowing this information can also cause some undue concern or anxiety over trying to predict when labor will actually begin. If knowing your dilation and effacement measurements in the last weeks of pregnancy is likely to make you feel more anxious than anything, remember that you have the option to decline cervical exams at your prenatal appointments (some cases where extra monitoring is required may warrant these checks, so always talk to your doctor about your options). Effacement and dilation both make birth of the baby possible, but remember not to get too hung up on data and measurements. When you start feeling consistent contractions that are measurable and increasing and intensity, you can take that as a good indicator that there are positive changes happening in the dilation and effacement of the cervix.