November 19, 2009

Cervical Dilation and Effacement

“Cervical dilation” and “effacement” are terms that you will hear your care provider talk about toward the end of your pregnancy and throughout your labor. These terms refer to the opening and thinning of the cervix. Dilation is measured in centimeters, from 0-10cm, and being at 10 cm means that you are fully dilated and can start push when you feel the urge to do so. Effacement is the thinning and shorting of the cervix measured in percentages, from 0-100%, and being at 100% means your cervix is paper-thin.

It is not uncommon for me to hear students come in and proclaim that they are 1cm dilated and expect labor to start any moment. Realistically, that is probably not going to happen. You can walk around dilated for several weeks before the onset of labor. As a labor support doula, I am more interested in how effaced a client is than how dilated. If the cervix is not shortening and thinning it doesn’t really matter much that it is has opened a bit. The cervix will not open significantly if it is not effaced very much. Once the cervix is on its way to fully becoming effaced, change in dilation will often happen.

What can you do to help effacement? The cervix becomes soft or effaced by the secretion or application of prostaglandins. “Prostaglandins are produced by the mother’s body as well as by the fetus and placenta.” (Holistic Midwifery pg 190) However, there are some other nonpharmaceutical ways to help ripen the cervix. Since semen contains prostaglandins, sexual intercouse is one of the best, natural ways to apply prostaglandins directly to the cervix. I know that toward the end of pregnancy, that may not seem all that appealing, so you can also insert evening primrose oil directly into the vagina. Please note: THIS IS NOT TO BE DONE IF YOUR MEMBRANES HAVE BROKEN! The recommended dosage is 2,500mg capsules a day. This can also be done by taking the oil capsules orally if you are not comfortable with inserting it vaginally.

Another natural method is called “stripping the membranes,” but again, note: THIS PROCEDURE NEEDS TO BE PERFORMED BY A MIDWIFE OR DOCTOR! It is done by the doctor or midwife inserting two fingers inside the cervix and separating the amniotic sac from the cervix. This may stimulate the body’s natural production of prostaglandin. “In two studies, sweeping the membranes successfully induced labor in half the cases attempted.” (Ina May’s Guide to Childbirth. Pg 216.)

If your cervix is not ripening on its own and, for a medically sound reason, your care provider is advising you to be induced, you will receive a vaginal suppository of either cervidil or cytotec. These both contain prostaglandins to help soften the cervix and make it favorable for dilation.

Take a look at the picture below to get an idea of how the cervix shortens and thins out.


Before moving on to discussing dilation, I also want to take a moment to mention the mucus plug. This is just an accumulation of secretions that forms a seal in the cervical canal. Its main function is to create a barrier for infection. As the cervix starts to change, the mother will notice the passing of the mucus plug. Some women describe it as clumpy mucus others experience the release as more of a stringy mucus discharge. The color can be anywhere from pinkish to slightly brownish. The passing of the mucus plug does not guarantee the rapid onset of labor, just an indication that some change is starting to happen.

Cervical dilation can best be described as the baby’s head pushing through a turtleneck sweater. It is the downward pressure applied directly to the cervix that causes the cervix to open. A well-applied head is regarded as being more efficient at dilating the cervix during labor. This pressure is made possible by the uterus contracting around the baby and pushing it downward. Gravity also helps apply pressure to the cervix, which is why squatting can be so beneficial and productive. If you are either stalled in labor or hit a plateau in dilation, it could be a result of poor fetal positioning. Read “Explanation of Fetal Of Position” for more details.

Although this is not to scale, you can get an idea of how the cervix widens and thins until there is no cervix left, at which point full dilation (10 cm) has been reached.
dilation chart

Also keep in mind that second or third time, mothers tend to dilate more, up to 3 or 4 cm before labor even starts. Some mothers may experience this kind of dilation for several weeks before the onset of labor.

The whole reason I was prompted to write this blog was the many questions and concerns that have come up in class. One mother was particularly concerned about doing yoga at 37 weeks pregnant, being 1cm dilated. I always refer to the care provider should there be a medical reason I am unaware of, but for most women, it is fine to continue your yoga practice right up until labor, dilated or not. I wish I could say yoga will help further efface or dilate the mother’s cervix and start labor. The best I can offer is that the yoga practitioner walks (or waddles) out of class more relaxed which is good for the hormonal cocktail that supports labor. But as far as I know, it can not jump start your labor.



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