Midwife Matters

As providers we often refer to a cervix as ripe or not at the end of pregnancy.  To many women this can be confusing and frustrating.  What exactly do we mean when we say your cervix is not ripe?  Here is what we are checking for:

• Typically a cervix is 3 to 5 centimeters long throughout a pregnancy.  As you get closer to the end of your pregnancy the cervix can start to thin out, or efface.  When we check your cervix we can feel how long it is from an exam.  If a cervix starts out at 4cm and is now 2cm that is called 50% effaced.  When the cx is completely thinned out, then it is 100% effaced.  How do we know exactly what your cervix was before…3cm, 4cm or 5cm?  We don’t, we make our best estimate.  That is often why you will get different numbers from different midwives.  Don’t worry, you are not going backwards like it may sound sometimes!

• Next we check the position of your cervix.  It can be posterior (meaning far back in the vagina), mid position or anterior (easy to reach, close).   Everyone is different, but most women tend to be posterior or mid during pregnancy.  As the cervix effaces and gets more ready for labor it will ordinarily be easier to reach or more anterior than it had been.

• A cervix during pregnancy is firm.  It should feel somewhat like touching the end of your nose.  A sign that your cervix is changing can be that it has gotten softer.  As pregnancy/labor advances the cervix usually becomes softer, sometimes almost mushy feeling.

• We also check where the head of your baby is, more commonly referred to as the station.  If it is engaged in the pelvis that is a 0 station, its head is at the ischial spines of your pelvis, which is the narrowest part of your pelvic structure.  Above the spines means the head is not engaged in the pelvis and is measured in centimeters but with a negative sign in front of it.  If the fetal head is 2cm above the spines, then the station would be -2.  As you move closer to the pushing stage of labor the fetal head advances past the ischial spines and it is again measured in centimeters but with positive numbers.  An example would be the fetal head is at a +1 station.  At a +5-6 station you can see the head at the entrance (introitus) of the vagina.  Up until the end of pregnancy the baby should not be engaged in the pelvis.  When we refer to the baby as ballotable, it means we can move the baby up and down in the uterus.

• Lastly we check the cervix for dilation.  During pregnancy the cervix is normally closed.  The last few weeks of pregnancy, especially if you have been pregnant before, the cervix can start to open or dilate.  This is not necessarily an indication that you will labor early.  Some women are dilated several centimeters weeks before they go into labor.

We put all of these assessments into a score called a Bishop score.  Each one of the above parameters is scored and then we add them up and come up with how ripe or ready your cervix is for labor.  If you are a first time mom a ripe cervix is a score of 8 or above.  For moms who have had a baby before it is 6 or above.  The higher the score the more ripe or ready your cervix is for labor.

Women often want their cervix checked at the end of the pregnancy during their prenatal appointments.  This is where you will hear the report if your cervix is ripe or not.  I have seen many women with an unripe cervix go into labor over the next few days and vice versa – a woman with a very ripe cervix go for many more weeks until labor begins.  In other words it doesn’t really mean much, so you shouldn’t worry about it.

The one time an unripe cervix does matter is if you need to be induced.  In that case we would start the induction with a cervical ripening agent and get your cervix more ready for labor.  This however doesn’t happen very often.  We try to induce only women who have a medical indication for inducing labor.  In my next blog I will discuss cervical ripening and how that is done.

Karin Marshall, CNM