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The ARRIVE trial

January 18, 2014

Labour induction for all at 39 weeks

The Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) i.e. the US government, has just funded a randomised controlled trial (RCT) to test the effect of inducing labour at 39 weeks for all women. It hasn’t yet started, but the details are all here.

The idea is that the risk of stillbirth rises after 39 weeks, and it is almost impossible to predict. So why not prevent it by inducing labour? Concerns that induction would increase Caesarean section rates have not been born out in other trials (click here), although they may not apply to this setting. It’s also vital to ensure that induction does not harm the baby.

  • Participants will be women in their first pregnancy, with a single baby, who have reached 38 weeks without any significant pregnancy complication.
  • The intervention group will have labour induced between 39w+0d and 39w+4d.
  • The control group will await spontaneous labour. Induction will be offered at the usual time of 40w+7d to 40w+12d depending on local policies, but not before 40w+5d.
  • The primary outcome is a composite of baby death, brain damage and other serious morbidity.

The plan is for 6,000 women to participate. The investigators hope to finish by June 2016.

It strikes me as rather a good trial. The question is important, and the hypothesis plausible. But we don’t want people offering induction to everyone without being sure it is safe and effective. Some women will rush to join, others will be horrified at the idea. Midwives and obstetricians will be equally divided. That’s why the research is needed. No-one is forced to join, so the trial is ethical.

I have two concerns. Why 39 weeks? Term, i.e. the mean gestation of a normal pregnancy, is 40 weeks. Why not first ensure that induction at term is safe? Secondly I doubt we could extrapolate the results, whatever they are, to the UK. US maternity care is very different; midwives are few and far between, and Caesarean rates much higher.

Perhaps we need an RCT of induction at 40 weeks in the UK.

Jim Thornton

10 Comments leave one →
  1. LAnderson permalink
    January 19, 2014 12:57 am

    Interesting study. Im in the no induction group of thought. I think when its ready its ready and it stays over time due to the mums inactivity. But I also knew a mum who lost bub suddenly at 42weeks. And hey, who says 40weeks is full term, its just an average number doctors came to, who says we cant go earlier or later?

  2. January 19, 2014 11:49 am

    At least two other ongoing trials. Our own 35-39, And Dutch INDEX trial.

  3. ConcernedResearcher permalink
    January 19, 2014 2:07 pm

    Perhaps we actually need to consider leaving labour alone to do its job and the damage caused to women and babies by the current intervention practices before starting a quest for a new one… If this trial is not going to follow mothers and babies into adulthood and look at every aspect of their development, physical and emotional health it risks ignoring some very, very important markers of long-term health. My suspicion is that in order to save a few babies there will be long-term risks to a large number of women and children.
    The risks of induction are already known, the long-term risks associated with a mothers emotional health are also well documented.
    This trial is asking permission to control a woman’s fertility in the dubious name of science by suggesting that neither her body nor her baby are capable of completing the job. The long-term risks of such strategies reach far beyond the ‘let’s get the babies out early and see what happens’.
    The implication that women’s being be free to join or not makes this trial ethical is missing some very important information from the concept of Informed Consent. If women are lead to believe that this strategy has more benefits than risks (which is going to be essential for women to join, as mothers simply do not knowingly put their child at risk) then they are not giving informed consent unless they are being counselled as to the risks of iatrogenic prematurity.
    Gestation takes as long as it needs for very good reasons, and until those reasons and the implications of doing otherwise are fully understood then a blanket policy of doing otherwise is a dangerous road to travel.

    • Helen permalink
      July 16, 2014 4:33 pm

      Very well put And I agree totally with everything you’ve said. This is a very slippery slope indeed.

    • Allison F permalink
      January 28, 2015 3:46 pm

      I think part of the issue here though is that we already do all of this, just at a different time point. We ‘routinely’ induce women at 41-42 weeks and a lot of women expect (and dare I say often welcome!) this deadline. It’s often not even considered a choice by many, just something that you do and only mavericks refuse. The emerging evidence about induction however suggests that this might not be the optimal time after all, if what induction is aiming to do is decrease the stillbirth rate whilst not overly increasing the risks to mother and baby.

      I tend to think what we could be doing a lot better at is presenting induction as a choice, being open and honest with each woman about the reasons why induction is being offered to her, explaining in a non-sensational way what the risks and benefits of induction are as opposed to awaiting spontaneous onset of labour (with reference to the risks and benefits as that woman sees it, not just the medical perspective), then supporting her to make a decision that is right for her.

      In theory this trial would offer good quality evidence about whether 39 weeks is the better time to offer induction but I do worry about the implications of telling a woman about the increasing rate of stillbirth, then randomising her into a control group where she categorically cannot access induction until at least 40+5. What you could get is a large number of women withdrawing from the study in order to access induction earlier – in the litigious US are the obstetricians going to refuse a woman who requests induction of labour in order to reduce her risk of stillbirth when all the evidence suggests that it would? But large numbers of withdrawals are a big problem for a RCT so it’s something worth considering.

  4. January 19, 2014 6:24 pm

    I have to say I agree fully with your comment ConcernedResearcher. As well as the obvious, immediate and short term potential complications of IoL, this has to be seriously considered And this

  5. January 19, 2014 7:38 pm

    Good points CR and Sheena. But I’m afraid we don’t know the long term effects of induction. The conclusions from observational studies are not clear cut. And the option of stopping inducing labour has long gone.

    The issue is do we just go on doing it, or not doing it, based on the whim of accoucheurs and parents? Or do we do some high quality research i.e. decent sized randomised trials to sort out the benefits and harms?

    Hopefully the US researchers will also measure softer outcomes and follow the babies up.

  6. Invisible Midwife permalink
    January 20, 2014 9:25 am

    These researchers have no soul and clearly no respect for a life nor knowledge of birthing physiology. Supposedly intelligent people experimenting on the future generation by evicting them from their mothers? Compromising 999 people to save potentially one more person per thousand? They haven’t explored or accepted the role that syntocinon/pitocin plays in human development but they seek to use it liberally in a trial??? They have no idea what they do and they DISGUST me. More power, more money than sense. In time we will look back and hang our heads in shame. Allowing a life to be compromised by unnecessary experimental birth practices and then expecting that person to journey their whole life with the results of them exploring their ‘hunches’.

  7. January 20, 2014 11:20 am

    Whilst I think trials are useful in many medical situations, as a mother who has gone through induction at 40+14, I think this trial risks the mental health of all the women who agree to induction at 39 weeks. Birth is not all about the baby, you know. You say ‘we don’t know the long-term effects of induction’ – well, that may be true when it comes to medical evidence of the baby’s development, but I’m afraid there are many women who would tell you the exact effect of induction on themselves, physically and mentally. Of all the women I know (or have heard of through friends), those who have been left traumatised by birth and frightened of doing it again are overwhelmingly those who have been induced with their first baby.

    I wholeheartedly disapprove of this trial. ConcernedResearcher puts it better than I do, but my emotional reaction (as one who has gone through induction which had a ‘good’ outcome for the baby but certainly not for me – and there was no medical reason to induce me except for the dates) is one of horror.


  1. How the consent process introduces bias into RCTs | The midwife, the mother and the breech

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