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By Professor Hannah Dahlen

Well everyone the ARRIVE trial has finally arrived. This was the elective induction of labour trial at 39 weeks. A total of 3062 women were assigned to labor induction, and 3044 were assigned to expectant management. The primary outcome of perinatal morbidity for the baby occurred in 4.3% of neonates in the induction group and in 5.4% in the expectant-management group (relative risk, 0.80; 95% confidence interval [CI], 0.64 to 1.00) (not significant). The frequency of cesarean delivery was significantly lower in the induction group than in the expectant-management group (18.6% vs. 22.2%; relative risk, 0.84; 95% CI, 0.76 to 0.93).

But here are some interesting details:

  1. It took over three years to recruit the women for the study and over 50,000 women were screened for eligibility with 22,533 deemed eligible. Only 6106 (27%) agreed to be randomised (acceptability was therefore low). This means 16,427 women did not agree.
  2. In the study 94% had a doctor as care provider and only 6% a midwife. We know care provider a major issue when it comes to rates of normal birth. Providers could not be blinded to group allocation and 94% had doctor care who are more pro induction, so you do the math.
  3. Women in the elective induction group gave birth on average at 39.3 weeks and in the expectant management group at 40 weeks (5 days difference).
  4. 280 women in the expectant management group had an induction or elective caesarean section and 366 in the induction group did not follow protocol for induction at 39 weeks (not clear exactly how many decided to await spontaneous labour)
  5. These women were very low risk and still 1:5 had a caesarean section
  6. No one is looking at long term follow up regarding the effect of increased exposure to synthetic oxytocin and other possible epigenetic implications

So in summary:

  • Most women said ‘no’ when asked to participate
  • Women were very low risk and still had a high caesarean section rate for this population
  • Women were not much different in their gestational ages in the two groups
  • Over 94% of women had medical care and only 6% midwifery (love to see a sub analysis on that group)
  • IOL at 39 weeks saved no more babies than waiting.
  • We have no idea about the long term effect

We must not arrive at conclusions too early on this one. Caution is needed. Let’s see this study repeated in a midwifery led population and see if the normal birth rate is impacted on. The problem with this would be that even fewer women would agree to be randomised which tells us one thing: induction of labour is not readily embraced by women!

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