What is cervical dilation?
During the 1st stage of labour, contractions make your cervix gradually open, this is called dilation and is used as one of the way to measure progress of labour.
The first stage is usually the longest stage of labour.
At the start of labour, your cervix starts to soften so it can open. This is called the latent phase and you may feel irregular contractions. It can take many hours, or even days, before you’re in established labour. Established labour is when your cervix has dilated to more than 4cm and regular contractions are opening and shortening your cervix until at 10cm it will be wide enough for your baby’s head to pass through.
It’s not like you can see it. But, to describe what it feels like I’ll start at the beginning.
At the top of the vagina is the cervix.
This is the entrance/exit to the womb – lets think of this as the gate, a thick locked gate that needs to completely open at 10cm dilation and your baby can pass through.
To begin with, the cervix is firm like the end of your nose and approximately about 2cm long. In the centre is a dimple of an opening but it is tightly closed and won’t admit a fingertip.
As labour progresses the first change is that the cervix becomes softer and softer and the length shortens a little more with each contraction. At some point the dimple in the centre widens and with the softening I can feel all the way through a tunnel like hole to the top of the baby’s head. This is known as dilatation.
In early labour this tunnel has defined sides and the cervix is still quite firm. As more contractions and hormones do their thing, the cervix feels more like a ring of playdough at first, the cervix is thick but soft with some stretch and depending on how wide two fingers can be admitted will determine how many centimetres.
For me I know that the distance between my two fingers fully stretched is 10cm and I use this as a gauge to judge lesser dilatations. Just for clarity, the pictures here are for easy reference – but personally I have never thought in terms of cookie or or bagel sizes although that might be helpful!
“Sophie, yes! I can feel you have reached cookie sized dilation, only an orange and bagel to go”
Almosts seems much less demoralising than “You’re only at 6cm – still some to go yet”
When contractions have shorted the cervix until there is no length or thickness, the cervix is termed as fully effaced. The cervix now feels balloon thin and stretches like the opening of a balloon (one that has been blown up and let down a few times) and if it is really stretchy, the consistency reminds me of mozzarella cheese.
With this elasticity, and if the baby’s head is in a good position, the dilatation is felt across the diameter between the cervix edges stretched tightly around the baby’s head. If the baby’s head is not in a good position I would be able to get my fingers in, under and around the cervix edges and they would feel floppy. A good position of the head will aid the cervix to dilate faster.
When a cervix becomes fully dilated – this is 10cm.
At this point I cannot feel any cervix around the baby’s head, it has completely stretched and thinned around the head and I cannot feel any of the edge of the cervix anywhere.
At this point the gate is fully open and mother will enter the second stage of labour.