Cervical Dilation Is Not Linear and Can Go Backwards!
It is often assumed that cervical dilation through labour follows a linear path and cannot reverse, i.e. You start at 0cm, increase to 1cm, then 2cm etc. all the way to 10cm, and that this happens at a constant rate and cannot go backwards.
This is not the case! Cervical dilation is unpredictable and can change dramatically from 1 minute to the next. It all depends upon the woman, the baby, and the environment in which they are. Dilation can go from full to partial and back again. However, in an environment where the woman feels safe and protected, where labour is uncomplicated and mother and baby are in good health, cervical dilation will increase and is unlikely to reverse, but very often this will not be in predictable increments i.e. 1cm per hour throughout the dilation.
Whilst all labours are different and will each follow their own trajectory, a typical western labour makes it difficult for a woman to follow the ideal. It is often broken into many sections; at home, the journey to the hospital, triage at the hospital, your room or ward at the hospital, then the delivery room! This process has a habit of interrupting the natural course of birthing hormones, introducing less desirable hormones and hindering progress.
There are many hormones that contribute to the smooth flow of labour and many that hinder it. Oxytocin is probably the most important hormone in aiding labour. Adrenaline is the main antagonist in hindering the progression of labour, and the release of adrenaline during the “first stage” of labour can effectively reverse labour and therefore dilation: This was a total surprise to us in the early days and we wrote about it here: Adrenaline: Bad For Labour? Huh!