Most people know that in order for a baby to make their wonderful debut to the world, their cervix (the bottom part of your uterus) has to open, or dilate. As people near the end of their pregnancy, often a common concern at the end of their appointment is “how dilated am I?” While dilation is an important part of the process, there are many other pieces that contribute to your cervix getting ready for labor and birth.

“Cervical ripening” is a term often used to describe the changes of the cervix as your body prepares for labor, and during early labor. This process includes dilation, but also how thinned out it is (called effacement), how soft your cervix is, and the position of your cervix in your pelvis. How low your baby is in your pelvis also plays into this equation, and is referred to as “station”. This process is slow, and often occurs over many weeks.

Here is an explanation of each part of the process:  

-       Dilation: Dilation is an easy concept to grasp – it is how open the inner most part of the cervix is (the opening near baby’s head) and is estimated in centimeters from 1-10 cm. 10cm technically means there is no more cervix in the way of baby’s head.

-       Effacement: Effacement is how thinned out your cervix is. Think of your cervix like a tube. Before someone is in labor, their cervix is roughly 4cm thick.  Over time as the cervix is preparing for labor, that tube becomes thinner. This is expressed in a percentage from 0-100%. For example, if someone’s cervix was measuring about 1 cm, then it would be 75% effaced (only 25% more needs to thin out). 100% effaced is just about paper thin.

-       Consistency: Your cervix begins to soften as is prepares for labor. Someone who is not close to labor would have a “firm” cervix, and feels like the tip of your nose. Eventually it starts to soften until it feels more like your cheek, making it easier for other parts of the process to occur.

-       Position: Your cervix moves from behind baby’s head close to your spine (called a posterior cervix) and makes its way to the top of baby’s head (anterior cervix). When it is anterior, it becomes easier for it to dilate and thin out since the baby’s head is applying direct pressure to the cervix.

-       Station: Station is how low baby’s head is in the pelvis. This piece is important because when a baby’s head is low, it adds more pressure to the cervix and helps with dilation and thinning out. This is measured in centimeters in relation to the ischial spines of your pelvis (the narrowest part of your pelvis), with the level of the ischial spines being 0 station. When baby’s head is higher than the ischial spines in the pelvis, we refer to the station as a negative, so -3, -2, -1. When the baby’s head is below the ischial spines, we refer to station as a positive, so +1, +2, +3…+5 is when baby is crowning!

So don’t get discouraged if you are told you are only 1 cm dilated – look at all the pieces of this process and be proud all the work your body has done! This process is different for everyone and can also change really quickly! And remember, as we often tell patients, you could be 1 cm dilated today and have your baby tomorrow, or you could be 3 centimeters and not have your baby for another week. =)

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