Cervical dilation is (now mathematically shown to be) unpredictable

6837374663_6b23e8379eCervical dilation is unpredictable. And we can now prove it with maths.

I realise that this will not come as a shock to most people who read my blog. And many people don’t need research to confirm their experiences. But I think it is important to share the findings of studies which add weight to traditional knowledge and/or progress our thinking about everyday areas. So it is in that vein that I share the following research.

A team of researchers in Italy has confirmed that, in spontaneous, naturally progressing labour, the rate of cervical dilatation is largely unpredictable.

That’s about it really.

Sure, they did really clever maths to get there, but I don’t suppose that many people will look that up. In part because those who know this won’t need the confirmation. And those who deny it aren’t likely to be open to changing their minds. They have too much of a vested interest in managing birth.

But, for those who would like to know, women who are left to their own devices will labour at their own pace.

Sometimes faster, sometimes slower. Sometimes in response to what is going on around them. And most times quite unpredictably.

Like I said though, it can be good to have studies to back up this kind of knowledge. And not just for the dull reason that we live in a world which seems to demand scientific proof of everything. Pretty much regardless of whether that is the best approach to investigating everything we want to know about.

3488377962_e546d8958dWatching scientists try to measure and predict the rate of cervical dilation in labour is somewhat similar to watching a cat chase the beam of light emitting from a torch that someone is projecting onto the wall.  Utterly pointless fun for a bit, but not something you’d want to spend a whole day doing. And maybe not fun at all for the women, who may be asked to undergo more vaginal examinations than usual in order to help ensure that enough data are gathered.

I do differ ever so slightly from the researchers on the question of what we do with this knowledge.

They conclude that, “future research in labor and delivery should be focused on the diagnosis of the causes that lie behind apparently erratic cervical changes”. I’m a bit unsure about whether this is appropriate or necessary or useful.

I agree that it’s all well and interesting to ask and study the patterns of nature, but I’m not convinced that diagnosis is generally a necessary feature of a normal, physiological journey. And frankly, I don’t think there are easy, linear relationships to uncover here.  So how about we redirect that research funding into teaching more people to watch and respect? Maybe even to knit? It would make a nice change to the constant measuring, meddling and messing about with what is a normal and healthy part of women’s lives.

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Ferrazzi E, Milani S, Cirillo F et al (2015).  Progression of cervical dilation in normal human labor is unpredictable. Acta Obstetricia et Gynecologica Scandinavica.  Online ahead of print. DOI: 10.1111/aogs.12719
photo credits: The Time and Light spot chasing fun both via photopin (license)

14 comments for “Cervical dilation is (now mathematically shown to be) unpredictable

  1. August 6, 2015 at 6:18 am

    As we have always thought and no need to fight back with research…….thankyou

  2. August 6, 2015 at 8:42 am

    Thanks for this Sara, I tell my couples this all the time, so it helps to have another person for them to refer to. I would like to put it on my Facebook page York antenatal classes if thats ok with you.
    Kind regards
    Hypnobirthing Practitioner (retired midwife)

    • August 7, 2015 at 5:53 am

      It’s fine to share it on your facebook page, but please link rather than copying and pasting, thank you 🙂

  3. May 31, 2016 at 12:45 am

    However, if you have multiple deliveries, it may help to know how you progress. Once I get to 5 I know I am within a few hours, and once I get to 7 I know I am minutes away from pushing.

  4. June 1, 2016 at 12:28 pm

    I wish I had understood this for my first birth when I was induced then put against the clock. For my second birth I declined vaginal exams and just trusted myself – so much better! It took me 3 days but that’s what we needed.

  5. Cathy
    August 6, 2016 at 1:36 pm

    With one of mine, my 3rd I think, I was examined and told I was “only 6cm”. The VERY NEXT contraction, I felt a strong urge to push. 4 or 5 pushing contractions, and the baby was here. It took me that many because I was trying not to push, what with being “only 6cm”.

  6. Stacey
    August 7, 2016 at 12:09 pm

    I think there is value is understanding that many labors take longer due to fetal positioning. Because then perhaps they would understand the value of getting moms up to move rather than just turning up the pit!

    • Linda
      August 10, 2016 at 3:13 am

      Who are the “they” you refer to? As a labour delivery nurse of 30 years and more, I am very aware that women are individual in how their cervixes change and how they progress in labour, and i am more than happy to allow them to proceed at their own rate as long as mom and babe are healthy and happy. However, an induction is hopefully being done for a reason and sometimes there are reasons a nurse cannot get them up to move around and her only recourse is to “turn up the pit”. Midwifery clients are theoretically low risk and there is perhaps more time to wait. Having a midwife bringing her client to the hospital with a them and us mindset is not helpful. We must work as a team, something I have worked for throughout my career. Please dont lump all hospital nurses as “they”.

  7. August 10, 2016 at 7:47 pm

    Ha ha- a useful piece of research that tells us ….just what we knew anyway! I am in complete agreement Sara with your comment about direction of future research

  8. Georgina
    August 12, 2016 at 11:18 am

    Perhaps they could focus their research efforts on why people like myself have a ridiculous cervix that likes to start opening at 23 weeks or thereabouts.

  9. Emily
    August 15, 2016 at 6:38 pm

    Last week I went from 3-4cm in 2 hours…. then 4-10cm in less than half an hour!!

  10. Jodie Mayfield
    August 16, 2016 at 4:13 am

    I’m a midwife from the UK but studying a masters degree (midwifery) in the US, and have come across very interesting research in my studies suggesting that the NICE guidelines really don’t give enough, barely any time in labor (surprise, surprise) to what women need to have a normal vaginal birth. Zhang et al. research is the latest buzz research in evidence for longer lengths of time needed whilst women are in labor. Length for 1st and 2nd should be given a lot longer time before intervention is initiated, eg UK before I left in 2013 women were ‘given’ 2hrs for 2nd stage (pushing), with Zhang et al research its shown to be normal to have 3/4hr pushing stage with epidural. Varney midwifery textbook gives a good overview of new research and gives the new ‘timings’ that should be initiated. Yes, I hate timings, but it seems the NHS likes them so at least this research is an upgrade on Friedman in the 1950’s which our labor system is still based on (1 or 2 cm per hour!!). Oh and 6cm is the new 4cm, so you can really only call active labor retrospectively, and most active labor may not start until at least 5 or 6cm. Hyperbolic curve is also the new buzz word – encouraging slower progress between 5-6, and expecting faster progress (a few hours) between 9 and 10. I wonder if the NHS is embracing this?? You can read a bit more about it here – http://www.obgynnews.com/single-view/use-6-cm-dilation-to-judge-labor-progress/37a4f40e561fe33b3aa7594c00de6622.html?tx_ttnews%5BsViewPointer%5D=1 Dr Tekoa King, is the author of Varney Midwifery and is a midwife.

  11. Jessie
    June 13, 2017 at 5:48 am

    I completely agree. Up until I read the conclusion I was nodding along, yes, yes. There are just different paradigms in operation. One that sees research supporting difference as reflecting our understanding of physiology and another which seeks to pathologise and standardise physiological processes.

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