Should I schedule an elective induction at 39 weeks?
… to reduce my risk of Cesarean
It all started with a Whatsapp message from my 37 week pregnant client.
In the message she attached a study she had stumbled upon. This study was claiming that scheduling an elective induction at 39 weeks would lower her chances of having a Cesarean.
Seemed like a no-brainer right?
“Welllllll” I warned her. “It's a bit more complicated than that”.
In 2018, a study was released in the New England Journal of Medicine that made huge waves in the birth community. This study concluded that for low risk, first time birthers, scheduling an elective induction at 39 weeks would reduce their chances of having a Cesarean Birth.
I’ve seen this study cited many times and I’ve had clients send me this study, asking for my thoughts on it.
Maybe your health care provider has suggested an induction at 39 weeks to reduce your risk of cesarean and you’re feeling unsure about it.
I hear you. These are big decisions you’re making. My hope is that after reading this blog post you will feel more confident and more empowered to have an informed discussion with your healthcare provider about whether an elective induction at 39 weeks is the right decision for you.
So let’s start by looking at the study in Question …
The ARRIVE Trial
In 2018, the New England Journal of Medicine published a study titled ‘Labour Induction versus Expectant Management in Low-Risk Nulliparous Women’ which is now referred to as the ARRIVE trial.
The primary purpose for this study was to look at whether an elective induction at 39 weeks (meaning no medically indicated reason) would result in any differences in neonatal health outcomes (either death or serious health outcomes). The secondary purpose of this study was to look at the effects that an elective induction had on cesarean rate.
The results from this study concluded that there was no difference in the primary outcome of the study (neonatal health outcomes) but there was a reduction in cesarean rates amongst the early induction group. While this wasn’t the primary purpose of the study, it has now become well known for this conclusion.
When you first read the results of this study, the results seem pretty conclusive but after taking a closer look, there are many elements to this study that need to be picked apart. While this study COULD be appropriate for some, it may not apply to you and your situation. Read on!
Some background on the study…
In the past, the question of whether elective induction effected cesarean rates was mainly studied observationally, and the general consensus was that an electively induced labour (vs. spontaneous labour at the same time), resulted in MORE cesareans (not less). So this study challenged the primarily held belief and is why it made such a splash.
Let’s start by acknowledging that there were many things about this study that were done really well. It was a randomized control trial which is the gold standard in research studies. It took place in 41 different hospitals across the United States and had over 6000 participants across both groups. It was well designed, well implemented, and deeply thought out.
There was a long list of criteria to be eligible to be in this study. To participate, you had to be low risk, nulliparous (which means first time giving birth). Low risk was defined as not having any pregnancy complications (there were a long list of criteria that excluded you from participating including gestational diabetes, hypertension, Intrauterine growth restriction, baby in a head down position, etc etc).
Due dates had to be confirmed by an early ultrasound. You couldn’t be planning an induction, cesarean, have premature rupture of membranes (waters breaking), or any bleeding.
If you want to see a FULL LIST of exclusion criteria you can do so HERE.
Around 6000 women were enrolled in the study and randomly assigned to one of two groups:
Group 1: Induction at 39 + 0 to 39 +4 (within this 4 day window)
Group 2: Spontaneous labour until 40 + 5, in which case they could choose to continue to wait, or be electively induced, until 42+ 2 when they had to be induced.
FIRST ISSUE: So, right off the bat, it’s important to understand that this study wasn’t actually comparing induction to spontaneous labour. This study compared elective induction at 39 weeks, to EITHER spontaneous delivery or induction at a later date. BIG DIFFERENCE.
A whole bunch of secondary maternal health outcomes were also studied including hypertensive disorders of pregnancy (gestational hypertension or preeclampsia), operative vaginal delivery, indication for chorioamnionitis, third-degree or fourth degree perineal laceration, postpartum hemorrhage, postpartum infection, venous thromboembolism, number of hours in the labor and delivery unit, length of postpartum hospital stay, admission to the intensive care unit, and maternal death etc etc (I won’t go into them all here) but you can read the study yourself HERE.
So … after all this data was collected, it was found that there were NO differences in neonatal outcomes (either deaths or serious health conditions) but those in the early induction rate had a cesarean rate of 18.6% vs the expectant management group of 22.2% and these results were statistically significant.
Does the ARRIVE trial apply to you?
This question, speaks to the external validity of the study, meaning, can this study then be generalized to other contexts? To figure this out, let’s look at who was in the study.
The first important thing to note, is that only 27% of eligible participants actually agreed to participate in this study. To put this differently, 73% of eligible participants declined to be in the study, or 17,000 folks.
This is an incredibly high number of participants declining to participate - and is a huge red flag when considering the generalizability of this study. But it also makes sense…
To participate in this study, you had to be willing to give up your choice on whether or not you would be scheduled for an induction. This on its own, is huge and excludes a whole group of people who are wanting to make informed and intentional decisions surrounding their birth.
You had to be willing to give up your choice in the matter.
Secondly, the cesarean rates in this study (in both groups!) were much lower than many US hospitals. In this study, the cesarean rate in the induction group was 18%, however other research has found rates around 30%, even as high as 50% or 60% in some hospitals. This makes me question how transferrable this study would be to real world scenarios.
We also have to look at the participants in this study, and whether they are a representative sample of the general population, or of you. Participants had a median age of 23 or 24 years, and had a median BMI of approximately 30 kg/m2. Does this sound like you?
And lastly, all of the participants within this study were birthing within a highly medicalized environment and 94% were under the care of physicians. Therefor it comes into question whether this study applies to anyone who is hoping to give birth outside of a hospital setting, and I would even argue a vast majority of people who seek out the midwifery model of care, who are looking for a low intervention model of care.
Where can we find biases?
Something else to consider, is whether the protocol for induction used in this study, mimics real life settings. It appears that the birthers in the early induction group were given a very long time to labour. The providers were incredibly patient with them, which may have contributed to their low cesarean rates.
One thing to consider is the doctors comfort levels supporting an induction at an earlier date vs either supporting an induction at a later gestational age, or spontaneous labour at a later date. The expectant management group gave birth on average later than the induction group (makes sense!). Typically, physicians are more comfortable being patient during a labour at 39 weeks, rather than a labour at 30, 41 or even 42 weeks and will often jump to a surgical birth earlier than necessary. This was indicated in that folks in the induction group spent more time in the labor and delivery unit than the expectant management group did.
There is something called a Hawthorn Effect in research, also known as the observer effect. This is when participants’ behaviours are altered, when they know they are being watched. This can highly bias a research study, and it’s been argued that this study is guilty of it.
The physicians in this study were being closely observed by the researchers and it’s possible that their behaviour changed as a result. This is evident in how long they waited for their patients to labour to ensure a positive induction (which doesn’t mimic many hospital statistics).
If lowering risk of cesarean is the primary goal, are there other, lower cost, lower intervention ways to do this?
The answer is very much YES. We have research showing us that there are a lot of things that you can do that can reduce your risk of cesarean by much more than 3-4%.
Here are some of the other practices that can reduce your risk of cesarean:
Continuous labour support (having a doula!)
Giving birthers with an epidural an extra hour to push (from 3 hours to 4 hours)
Planning a birth in a birth centre
Planning a water birth
Walking around during first stage of labour instead of being confined to bed
All of these changes to care, are simpler and cheaper!
The Effects of the ARRIVE Trial
One of the most interesting repercussions from this study, is how much it has impacted obstetric practices since it’s publication in 2018.
There have been research studies published that have looked at how the ARRIVE trial has changed general induction practices. Induction rates HAVE gone up, since the publication of the ARRIVE trial, but whether these are having positive effects on cesarean rates and maternal and perinatal health outcomes is up for debate.
Results have come back mixed with some research showing that the rate of cesareans have gone down, while others showing no change, or an increase. Almost all studies have shown that elective inductions have increased though, indicating how this one study has really changed obstetrical practices!
It will be interesting to see how this research study continues to change obstetric practices in the future.
Final takeaways
With any study, regardless of how well it is done, it all comes down to context.
The folks in this study were all giving birth within a medicalized environment. They were being cared for primarily by physicians, there is a higher chance they received epidurals, pitocin, etc.
If you’re giving birth within the medical model of care, in a highly medicalized context, if your demographics fit those from this study, and if you are un phased by whether you have an induction or not, then you might lower your risk of a cesarean by 3-4% if you are induced at 39 weeks. This is probably more probable for someone at a higher risk of developing a pregnancy complication like for example pre eclampsia or hypertension.
This study however is probably not appropriate to anyone who is choosing the midwifery model of care, a low intervention, low medical model birth, and wants to make informed decisions about their birth.
If a cesarean birth is something you would like to try to avoid, there are many other, lower cost, higher effective ways to reduce that risk!
Did you enjoy this Blog post? Then you may also enjoy the following blog posts:
Should I use an epidural during childbirth?
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