Cervical Dilation and Effacement Prior to the Onset of Labor: What Does it Mean?

Here's the short answer: nothing.

These days, so much stock is put into how dilated and effaced a woman is in the weeks leading up to her due date. Moms consent to routine vaginal exams and anxiously wait to hear from their care provider if they've progressed at all. If they have, they get ridiculously excited and think that this means labor will start any minute. If they haven't, they get disheartened and wonder if their body will ever go into labor on its own.

Some moms, like me, dilate and efface early. With my first, I was 2cm dilated and 75% effaced at my last OB appointment before I went into labor, I had already lost my mucous plug. I started dilating 2 weeks before my daughter was born, which was nearly a week before my projected due date. Dilation obviously did not mean she was ready to be born. With my second, I had prodromal labor from about 36 weeks until she was born at 38 weeks 6 days, and for pretty much that entire time, I was 4cm dilated and about 60-80% effaced. For just shy of 3 weeks, I was far enough dilated for some doctors to call it active labor. But I was not in active labor, and if they had augmented or tried to speed up my labor as soon as those signs appeared, my daughter would have been born too early. Just because there is dilation and effacement (and sometimes contractions) present, does not mean labor is imminent within any definable time period. Yes, it's good to know that your body is preparing, but it does not mean that you will go into active labor in X amount of hours/days/weeks.

Other moms do not dilate or efface at all before they go into labor. I've heard of mothers who went in for a routine appointment in the morning, were examined and had not dilated at all, and had their baby that night. If you are wanting or needing to be induced, it is best to do so with a "favorable cervix" (a cervix that is far forward, soft, and beginning to dilate and efface), but not being dilated or effaced does not mean that you will not go into labor in X amount of hours/days/weeks.

Basically, if you're dilated before you hit active labor, that's great! That's that much less work you have to do once things get going, but it doesn't tell you when it will get going. And if you're not dilated, then, that really doesn't mean anything either! So my thinking is, unless you're considering induction, or there are any red flags like bleeding or regular contractions, why even have vaginal exams? They aren't going to give you any insight into your labor, really, and they do carry the risk of introducing infection, accidentally breaking your water, and kick-starting labor (which isn't always a good thing).

Here's a couple of further explanations:

 

"Is Cervix Dilation an Early Sign of Labor?

Ultimately, cervix dilation is necessary for labor to progress. If the cervix doesn't open, then the baby can't be born vaginally. But is cervical dilation necessarily an early sign of labor?

Not necessarily. A woman can remain 4cm dilated for weeks before true labor begins or can go from no dilation to natural childbirth within a few short hours. The degree of cervical dilation prior to the onset of labor is not a reliable indicator of when true labor will begin. Women can dilate several centimeters weeks early, contemplating the arrival of a preterm baby, and then remain at that same degree of dilation for weeks or go from zero dilation to having a baby in mere minutes.

The following cervical dilation chart illustrates the diameter of the cervix as it opens from 1 to 10cms. 1cm roughly equates with a Cheerio, 3 cm with a slice of banana, 4cm with a Ritz Cracker, 7cm with the top of a soda can, and 10cm with a bagel.

As cervix dilation itself is not a reliable predictor of when labor will begin, knowing the degree of cervical dilation in advance of active labor is of little benefit. It also carries unnecessary risks, the first of which is introducing infection. It also increases the risk of starting preterm labor.


Internal exams are not recommended for the above reasons until after 41 weeks when potentially facing a postdate induction. Then, cervical dilation can provide valuable information on whether induction is likely to be successful at that point."

 ( http://www.givingbirthnaturally.com/cervix-dilation.html )

"The Myth of a Vaginal Exam

Why a Vaginal Exam at the End of Pregnancy Might Not Be What You Think

Vaginal exams. I don't know a single woman who likes them.
However, there is a myth perpetuated in our society that vaginal exams at the end of pregnancy are beneficial. The common belief is that by doing a vaginal exam one can tell that labor will begin soon. This is not the case.
Most practitioners will do an initial vaginal exam at the beginning of pregnancy to do a pap smear, and other testing. Then they don't do any until about the 36 week mark, unless complications arise that call for further testing or to assess the cervix. If your practitioner wants to do a vaginal exam at every visit, you should probably question them as to why.
Vaginal exams can measure certain things:

• Dilation: How far your cervix has opened. 10 centimeters being the widest.
• Ripeness: The consistency of your cervix. It starts out being firm like the tip of your nose, softening to what your ear lobe feels like and eventually feeling like the inside of your cheek.
• Effacement: This is how thin your cervix is. If you think of your cervix as funnel-like, and measuring about 2 inches, you will see that 50% effaced means that your cervix is now about 1 inch in length. As the cervix softens and dilates the length decreases as well.
• Station: This is the position of the baby in relation to your pelvis, measured in pluses and minuses. A baby who is at 0 station is said to be engaged, while a baby in the negative numbers is said to be floating. The positive numbers are the way out!
• Position of the baby: By feeling the suture lines on the skull of the baby, where the four plates of bone haven't fused yet, one can tell you which direction the baby is facing because the anterior and posterior fontanels (soft spots) are shaped differently.
• Position of the cervix: The cervix will move from being more posterior to anterior. Many women can tell when the cervix begins to move around because when a vaginal exam is performed it no longer feels like the cervix is located near her tonsils.

What this equation leaves to be desired is something that is not always tangible. Many people try to use the information that is gathered from a vaginal exam to predict things like when labor will begin or if the baby will fit through the pelvis. A vaginal exam simply cannot measure these things. Labor is not simply about a cervix that has dilated, softened or anything else. A woman can be very dilated and not have her baby before her due date or even near her due date. I've personally had women who were 6 centimeters dilated for weeks. Then there is the sad woman who calls me to say that her cervix is high and tight, she's been told that this baby isn't coming for awhile, only to be at her side as she gives birth within 24 hours. Vaginal exams are just not good predictors of when labor will start.
Using a vaginal exam to predict advisability for a vaginal birth is usually not very accurate, for several reasons. First of all it leaves out the factor of labor and positioning. During labor it's natural for the baby's head to mold and the mother's pelvis to move. If done in early pregnancy it also removes the knowledge of what hormones like Relaxin will do to help make the pelvis, a moveable structure, be flexible. The only real exception to this is in the case of a very oddly structured pelvis. For example, a mother who was in a car accident and suffered a shattered pelvis or someone who might have a specific bone problem, which is more commonly seen where there is improper nutrition during the growing years.
During labor vaginal exams can't tell you exactly how close you are either, so keeping them to a minimum then is also a good idea, particularly if your membranes have ruptured.
Okay, so there's not really a great reason to have a vaginal in exam done routinely for most women. So are there any reasons not to have vaginal exams? There sure are.
Vaginal exams can increase the risks of infection, even when done carefully and with sterile gloves, etc. It pushes the normal bacteria found in the vagina upwards towards the cervix. There is also increased risk of rupturing the membranes. Some practitioners routinely do what is called stripping the membranes, which simply separates the bag of waters from the cervix. The thought behind this is that it will stimulate the production of prostaglandins to help labor begin and irritate the cervix causing it to contract. This has not been shown to be effective for everyone and does have the aforementioned risks."

( http://pregnancy.about.com/cs/interventions/a/vaginalexam.htm )



So to conclude, don't treat your cervix as a magic 8 ball or crystal ball that can help you predict when your labor will begin. It doesn't work like that. Doctors still can't figure out what exactly it is within the mother and baby that triggers the onset of active labor, and every woman (and each of her pregnancies) is different in terms of speed, dilation, presentation, etc., so simply assessing dilation and effacement before labor starts isn't going to give you any solid clues. Vaginal exams are not risk-free, either, so think twice before consenting to or asking for them if you or your doctor are simply curious. Is knowledge that will either tantalize you (already dilating or effacing) into thinking that labor could start any second, or discourage you (not dilated or effaced) into thinking you might never go into labor naturally, really worth the possible risks it poses? If there is a concern that could be put to rest by a vaginal exam, or bring a problem that needs to be treated to light, then of course the benefits outweigh the risks. Any information on cervical dilation and effacement, in a healthy mom, when approaching her due date, is not going to tell her anything useful about when her labor will start or what it will be like. So let's stop disappointing ourselves by focusing on that information and what it doesn't tell us, and instead try to relax (easier said than done, right?) and let our bodies do their thing without adding any extra stress.