The long muscles of the uterus reach down, gradually pull back on the circular muscles of the cervix these are felt as contractions.
They are softening & shortening the cervix (effacement) pulling it into the body of the uterus (dilation) until it’s open wide enough for the baby’s head (approximately 10cms)

Internal examinations are a choice they are NOT compulsory.
They give you a snap shot of what is happening at that moment in terms of progress and where you are in the process.

Hospital guidelines suggest a woman’s cervix will dilate ½ cm/hour.

Cervical dilation is not the only indicator and things can change so rapidly with babies being born a few contractions later or taking their own sweet time.

Most hospitals would be unwilling to admit a woman until the cervix is at least 4cm – 5cm dilated because it is only then she is deemed to be in ‘active labour’ (although there is new research which suggests women are not in ‘active labour’ until the cervix is 6cm dilated – Sarah Wickham, 2018).

Unfortunately, despite this form of measurement being extraordinarily inaccurate, it has become the ‘norm’ for assessing a woman’s labour. Just as with a photograph, you can’t say what happened just before the photo was taken and you can’t say what’s going to happen after. Therefore, ascertaining the cervical dilation at a particular point, doesn’t really give a lot of information.
I have been at births where it has taken the mother ages to get to 3cm but 2 or 3 contractions later she is holding her baby in her arms. Similarly, one mother I was with was at 9cm and there was no baby for another 7 hours.

If mother and baby are fine and healthy there should be no pressure to rush the process. Every woman is different … and so are their cervix’s!

First time mothers will generally take longer to get to that ‘magic’ 4cm – 5cm because the contractions need to bring their cervix forward (it’s posterior during pregnancy i.e. pointing backwards), then soften it and then open it. So even if you’re examined by a midwife and told you’re ‘only’ 2cm dilated, remember that your uterus has already done a fantastic amount of work to get to that point, and you should be feeling rather chuffed with yourself that you’ve reached that stage.

There is a fantastic You Tube video doing the rounds lately, involving a balloon and a ping pong ball (Google it, the woman who posted it is called Liz Chalmers) which demonstrates exactly how much work the uterus has to do before it can even start. Second time mothers generally (although not always) tend to have quicker labours because their bodies know what to do if they have reached full dilation before, due to muscle memory. The labour hormone receptors also tend to be more efficient.