Emily Oster and Nathan Fox

22 minute read Emily Oster and Nathan Fox

Emily Oster

Nathan Fox

Choosing to Induce

How a randomized trial gave birth to a new era in obstetrics

Nathan Fox

22 minute read

One of the most common questions I get as people move to the end of pregnancy is Should I have a labor induction? Labor induction did not used to be the norm, but it increasingly is. In many medical practices, it is not routine to schedule labor induction at 39 weeks of pregnancy for virtually all patients.

A big reason for this change is something called the ARRIVE trial, which was designed to test whether routine induction would increase the risk of cesarean section. The results were published in 2018, and they showed that labor induction did not drive C-section rates. In the wake of the trial, with that concern limited, many more doctors began recommending inductions as routine.

But this doesn’t work for everyone — some people would rather not be induced, and some researchers have argued that the results from ARRIVE actually do not hold up in the real world. Today on the podcast, I bring on my friend Dr. Nathan Fox so we can dive into data and decision-making on this tough question. Dr. Fox is a maternal fetal medicine specialist in New York and my co-author on our new book, The Unexpected, which is out in April.

To spark your interest, here are three highlights from the conversation: 

How do doctors know if you need an induction? 

Emily:

What are the kinds of things that would make you want to induce versus wait?

Dr. Nathan Fox:

Basically, since there was this idea that if you induce labor you’re increasing the risk of C-section, we would always weigh the benefits of induction versus this risk of C-section. So for example, if I was worried about an increased risk of stillbirth or if I was worried about the mother having an infection or if I was worried because her blood pressure’s going up and she may or may not have preeclampsia, which is unsafe. So we’re balancing the risk of inducing, which is C-section, versus the risk of not inducing or staying pregnant, which could be something bad to the mother or baby. And based on the specifics of the situation, or the condition, we make a decision: all right, we shouldn’t induce, will we wait longer? Will we not wait longer? 

And that’s how we did it then, but people started to question that basic fact — that C-section is increased by being induced. And the first way they did it is they went back and looked at the same data that they used to conclude that induction increases the risk of C-section, but they looked at it differently. Instead of looking at women who are in labor versus induced, they looked at a week earlier, people who were induced versus people told to go home. And when they did it, again, retrospective observational, even in those studies, when they reexamined it in a way that makes more sense clinically, they saw no difference in the rate of C-section between the groups. 

And that’s actually what prompted the ARRIVE trial. They said, “Whoa, wait a second. When we look at the data in a more logical way, or a more clinical way, this may be wrong. We may have been telling people the wrong thing for all these years. We need to do this in a really well-designed prospective trial.” 

When is the best time for an elective induction?

Dr. Fox:

I don’t think it’s unreasonable to say, “I think the best strategy is to induce everybody at 39 weeks because it does not increase the risk of C-section” and because it might lower the risk of that. Okay, but that doesn’t mean it’s the right answer for everyone, because again, there’s logistical issues. There are patient preference issues. “I don’t want to be induced at 39 weeks, I don’t want to have a 24-hour labor. I want to wait and go into labor of my own.”

So what I tell people typically is any time between 39 and 41 weeks, and maybe for some people 42 weeks, is a reasonable time to be induced. And there’s benefits to going earlier, towards 39 weeks, and there’s benefits to waiting longer, towards 41 weeks. And unless there’s a real medical issue at hand, no one could say that one benefits are better than the other benefits.

If you’re someone who wants to be done as soon as humanly possible — you don’t feel well, you’ve got people coming in town, whatever it is; you want to be delivered at 39 weeks — I’ll say, “Fine, if we can get a room. Just be prepared for a long induction, God bless.” And if they want to wait till 41 weeks, the downside is, well, you’re pregnant for two weeks more, you may not go into labor, and you may end up with an induction anyway, and there’s small risks to you and to the baby, very slight. I don’t try to scare people or anything, but there’s very small risks of waiting longer in pregnancy. And that’s it. And most people will tell you what they want, most people will show you their cards. It’s not that hard.

How do you talk to your doctor about a possible induction?

Dr. Fox:

I would say that one of the important aspects about induction is asking, “Why are you recommending this?” Right? Are you recommending it just because I’m 39 weeks and I’ve hit a certain number, but everything is going perfectly fine, in which case I think there’s a lot of room for waiting and pushback — like maybe I don’t want to induce, versus are you recommending it because you have a specific concern for me or my baby about waiting on top of just the, I’m getting more pregnant? Meaning, is it because I’m 45 years old and you’re worried about a risk of a stillbirth? Is it because I have diabetes and you’re worried about a risk of a stillbirth? Is it because my blood pressure’s creeping up and you’re worried about me getting severe hypertension? That’s a very different reasoning than “just because.” 

And again, just like patients will tell you what they think, doctors and midwives will tell you what they think. We’re not secretive. Our personalities come out, our opinions come out, and you want to get a sense. Ideally, these conversations should happen early in pregnancy — not specifically about induction, but just in general, because you’ll get a sense, is this a person I trust. And if it’s a person I trust, then probably this conversation will be very easy because you’ll already have that rapport. If you’re not sure if you trust this person, that’s not a good place to be.

Emily:

I wish I had had that advice with my first pregnancy, because I remember getting to the end and telling the doctor, “I’m planning not to have an epidural.” And they were like, “Oh, yeah, we’ll see how that goes.” And I was like, “Oh, we should have touched on this earlier.”

Dr. Fox:

It is true that, at least in our hospital, 90% of women get epidurals. That’s just sort of the numbers, but if you’re going to be in the 10%, I think that’s awesome. As I say, your labor won’t hurt me one bit, so whatever works, great. I think it’s terrific. 


Full transcript

This transcript was automatically generated and may contain small errors.

Emily Oster:

This is Parent Data. I’m Emily Oster.

One of the most common questions I get about the end of pregnancy is whether it’s a good idea to have a labor induction. For those of you who are wondering what this is, for many people at the end of pregnancy, they go into labor on their own. That’s called a spontaneous labor. But sometimes it makes sense to induce labor, to encourage labor, to start using a combination of medications. Over the past several years, there has been a push towards more of these labor inductions, and for many more people, they are being offered or even actively encouraged to induce labor at the end of their pregnancy. For some people, this is really welcome. A lot of the feelings of pregnancy are about giving up control, but the possibility of having some of that control back, at least for a little while, of being able to pick when you have your birth, that seems appealing. It’s easier to plan around. But for other people, this isn’t what they want. They were thinking of their labor experience as something that would start on its own, and being offered or strongly encouraged towards an induction makes them uncomfortable.

The reason this has changed so much in the last few years is because of something called the ARRIVE trial, which we’ll explain at much more length in this episode. But the most important baseline thing to understand is that this is a randomized controlled trial. It was designed to test whether labor induction made C-sections more likely. That was one of the concerns about labor induction. And what the trial showed is that it didn’t. The group that had their labor induced was no more likely to have C-sections than the group that didn’t have their labor induced. And a result of that is that many more providers became comfortable with the idea of labor inductions, and as they became more comfortable, we started to move towards a world in which maybe everyone should have a labor induction. After all, it’s easier to plan. It’s easier to schedule.

This landscape, this moving landscape, has caused a lot of tension, a lot of discomfort for a lot of women. And today I’m going to talk with Dr. Nate Fox about induction, about this trial, about what we should learn from this trial, what we shouldn’t learn from the trial, about the limits of evidence in general, and also about how we bring our own preferences to our care. We talk about the risks of induction versus the risk of waiting, and we really try to get into how people can make this decision in the most informed way for themselves.

A quick note. Nate and I talk about ACOG, which stands for the American College of Obstetrics and Gynecology, just to be clear on that one.

After the break, Dr. Nate Fox.


Emily Oster:

Hello, Nate.

Dr. Nathan Fox:

Hey.

Emily Oster:

Welcome to ParentData. Can I ask you to introduce yourself?

Dr. Nathan Fox:

Yes, you can. Thanks for having me. My name is Nate, or Dr. Nathan Fox formally, but that doesn’t usually happen. So I am a, let’s see, I’m an OB/GYN and maternal fetal medicine specialist. I am in practice in New York City, and I’m originally from the Midwest, which explains my pleasant demeanor. And I live in New Jersey with my wife, and I have four children, some in the house, some moved out of the house, and two dogs.

Emily Oster:

So you’re also, your most important job is you’re my co-author on our book, the Unexpected, which is coming out at the end of April. Would you say, is that your most important role?

Dr. Nathan Fox:

Yes. It certainly appears to be the most impressive thing I’ve done in the past several years. If you ask anybody in my life, they’re like, “How the hell did you get roped in with Emily Oster?” But yeah, no, it’s been awesome. I’ve been very pleased to do that, and I’m really excited about the book and it’s going to be great.

Emily Oster:

I agree. Okay, so today we’re going to talk about the ARRIVE trial, and I actually want to structure the way we’re talking about this and sort of before, during, and after. And so to start with the before, so in the years, and really the decades, before this trial, including when I wrote Expecting Better, I think a lot of people saw induction as part of what they would call the cascade of interventions. I believe that phrase is from Ricki Lake, and the concern-

Dr. Nathan Fox:

The great philosopher Ricki Lake.

Emily Oster:

The great philosopher Ricki Lake. And the concern was that labor induction would lead to a stalled labor, which would then ultimately lead to a cesarean section. And from a data standpoint, that conclusion, my sense is, was based on the observation that people with induced labor are more likely to have cesarean sections than those who start labor spontaneously. Obviously, in a lot of cases there are underlying risk factors which drive the decision to induce and make people more likely to need a cesarean. It’s very difficult to draw a causal conclusion from that data. So from your standpoint, in this kind of pre-ARRIVE trial period, how did you think about the consequences of labor induction for C-sections?

Dr. Nathan Fox:

Yeah, it’s a great question, and it’s an interesting topic now, it was certainly an interesting topic then. When you mention the term cascade of events, it’s interesting because a lot of people use that term and what they typically use it to mean is, well, once you go to a hospital or go to a doctor, they’re going to start doing this and it’s going to lead to that, and it’s going to lead to that, and ultimately it’s going to lead to world destruction or something like that. But labor induction really wasn’t part of the cascade because it was really considered, itself, something you really should not do. It wasn’t like because it’ll lead to A to B to C, it was like you should not induce. And during my training and during the beginning part of my practice, the tenet was that we know that if you induce someone’s labor you are going to increase their chance of a cesarean delivery. That is the biggest downside.

Emily Oster:

That was something where it was like, we know that’s true. That’s something we accept as part of our, or at least we think is true.

Dr. Nathan Fox:

Well, that’s what was taught. I disagreed at the time, I’ll explain why and I think that I’ve been vindicated, but that’s what we were taught. That was in the textbooks. That was what you were taught first day of your first internship. If you induce labor, you’re increasing the risk of C-section. That was the biggest downside. And then the other downsides, in terms of patient experience, it’s going to take longer, which are all true, fine. But the problem was, and this was a problem at the time, the data was poor or limited, and the reason the day was limited is basically what they did is imagine if I went onto the labor floor and we have a labor board of, let’s say, 20 patients are in labor. And I say, “All right, patients one through 10, just so you know, all showed up in spontaneous labor. And patients 11 through 20 are here, they’re getting induced.”

It is true that patients 11 through 20 had a higher rate of C-section than patients one through 10. And so the conclusion people made is, “Okay, people who are getting induced have a higher rate of C-section than those who come in spontaneous labor.” True statement. The problem is, clinically, if I’m seeing someone and making a decision about whether to induce them or not, the alternative to being induced is not you shall be in labor, it is go home. And so we don’t really have an opportunity, clinically, to decide whether someone should be induced or be in labor. We have a decision whether to induce them or not induce them, which means I’m going to send you home and come back when you’re in labor, or in a week or whatever. And so that was not advertised as part of the conclusion that induction increases the risk of labor. And so when they-

Emily Oster:

Nate, just to pause on that, what are the kinds of things that would make you want to induce versus wait?

Dr. Nathan Fox:

Right, so basically since there was this idea that if you induce labor you’re increasing the risk of C-section, we would always weigh the benefits of induction versus this risk of C-section. So for example, if I was worried about an increased risk of stillbirth or if I was worried about the mother having an infection or if I was worried because her blood pressure’s going up and she may or may not have preeclampsia, which is unsafe. So we’re balancing, all right, the risk of inducing which is C-section, versus the risk of not inducing or staying pregnant, which could be something bad to the mother or baby. And based on the specifics of the situation, or the condition, we make a decision, all right, we shouldn’t induce, we shouldn’t induce, will we wait longer? Will we not wait longer? And that’s how we did it then, but people started to question that basic fact, that C-section is increased by being induced. And the first way they did it, is they went back and looked at the same data that they used to conclude that induction increases the risk of C-section but they looked at it differently.

Instead of looking at women who are in labor versus induced, they looked at a week earlier, people who were induced versus people told to go home. And when they did it, again, retrospective observational, even in those studies, when they reexamined it in a way that makes more sense clinically, they saw no difference in the rate of C-section between the groups. And that’s actually what prompted the ARRIVE trial. They said, “Whoa, wait a second. When we look at the data in a more logical way, or a more clinical way, this may be wrong. We may have been telling people the wrong thing for all these years. We need to do this in a really well-designed prospective trial.” And that’s what led to the ARRIVE trial.

Emily Oster:

So we’re going to get the ARRIVE trial in a second, but just to sort of put a fine point on why this initial data is not good, or is not necessarily compelling, it is this issue of, you mentioned preeclampsia, stillbirth risks, infection risks or characteristics that would push you to say, “Hey, let’s induce now. Let’s not wait, let’s induce now.” Those are characteristics which themselves lead to a higher risk of C-section for, I would guess, a bunch of reasons. For example, if labor starts to get a little more complicated, you’re going to be more likely to pull the trigger on a C-section because you’re worried about other risks, or worried about other aspects of the baby. Is that basically the issue?

Dr. Nathan Fox:

Potentially. I mean, when you have a situation where there’s concern like preeclampsia or something like that, the reason to induce is not because I want to lower the risk of a C-section though, it’s because I want to lower the risk to the mother and baby. So we say even if it does increase the risk of C-section, we’re willing to take that risk because we’re helping the mother baby. But yes, it is possible that in fact it would lower the risk of C-section because we don’t know what’s going to happen, because no one tends to wait on those patients. But they did start to chip away at this idea of induction increases the risk of C-section, and they did it in sort of subsets like women with ruptured membranes. There’s old, old data that if you induce them you don’t increase the risk.

Then they did it for women who had hypertension. And the same thing, if you induce them, you don’t increase the risk. Then they did it for women who are over 35, and if you induce them you don’t increase risk. Meaning there was more and more mounting evidence, at least in smaller populations, that maybe this is incorrect. And the reason you would want to know that is number one, just in terms of counseling, and number two, it may change, it may tip the scales. You may need less of a risk of waiting to push you over the edge to induce if you’re not worried about the risk of induction. Maybe even to the point, and I’m not suggesting that you need to do this, but maybe to the point that you should just induce everyone. I mean that’s sort of the possible conclusion from something like this.

Emily Oster:

Yeah. Okay. So then we have this kind of suggestive evidence, which the way that I would frame it is once you limit to people where you know the reason for induction, and the reason for induction isn’t something that itself would lead to a risk of C-section, then you’re starting to get evidence that it doesn’t matter. So then we get-

Dr. Nathan Fox:

Or in general. Again, even in the general population because they looked at people who are induced electively. And also, this is really also talking about first-time moms, meaning even back then, way back when, before the ARRIVE trial, if you’re taking someone who’s already had a baby vaginally, yes inducing might increase the risk of a C-section but only by a couple of percent points, not by a really massive difference.

Emily Oster:

Once you have already had a vaginal birth, it’s all loosened up, so it just slips right out.

Dr. Nathan Fox:

They just walk right out.

Emily Oster:

That was so nice.

Dr. Nathan Fox:

Yeah.

Emily Oster:

It’s just like they’re basically, okay. All right, so then we come to the ARRIVE trial. So this is a trial, a large randomized controlled trial, was published in the New England Journal of Medicine in 2018. The aim in this trial is to evaluate whether routine labor induction at 39 weeks of pregnancy makes a C-section more likely. The trial includes about 6,000 low-risk women having their first child, and it randomized them into either induction at 39 weeks or expectant management, which is just another word for just sending them home and waiting.

They actually, of course, as always at a trial like this, they weren’t forced to make the choice they were randomized into, but in the end, because of this encouragement, groups did have very different induction rates. And the results, what the authors find is that infant outcomes very similar in both groups. And if anything, there is a slightly lower C-section rate in the group that was induced. So both groups are actually very low, which we’ll come back to. It’s about eight to 11% of births are C-sections, that’s relative to a US rate of about 30%. But on face value, this trial really puts a wrench into the idea that labor inductions increase the risk of C-sections. So when this came out, did you just say, “I told you so?”

Dr. Nathan Fox:

I’m not a big I told you so guy, but it was definitely… Yeah, you would think I am. No, I mean, even to those of us who were sort of questioning that idea, I think a lot of us were still surprised how much it really didn’t seem to matter. And like you said, maybe a slightly lower risk of the group that got induced. I don’t-

Emily Oster:

It’s a pretty small difference.

Dr. Nathan Fox:

Yeah. I don’t make too much of that. As expected, the group that got induced had a slightly lower risk of getting hypertension, because as you wait longer in pregnancy that risk goes up. So that was not a surprise, but the fact that it really did not impact C-section rates, it was definitely surprising to everybody. But even those of us who are knee deep in it already, we’re still a little bit like, “Oh, pretty cool.” It was a very impressive study and it absolutely changed the way a lot of people think about induction. I think, correctly, it changed the way, I’m sure we’ll discuss it, I think some people might go a little too far with this, but whatever, it was impressive. It is impressive.

Emily Oster:

So let me ask you for you, and then I want to talk about the more general question. But for you, did this change how you advise people? Did it change your clinical practice?

Dr. Nathan Fox:

So, yes and no. It didn’t ultimately change my clinical practice because before the ARRIVE trial I was talking to people about risks and benefits of induction versus expected management. But ultimately, since the only reason we would really induce people is because of a medical indication, it didn’t really make a big difference. We were already inducing people who needed to be induced. The people who it really affects are people who are thinking about, what we call, elective inductions, just getting induced because I don’t want to be pregnant anymore, which is, God bless, that’s a very reasonable feeling to have.

But whether it’s a problem to induce for that reason, that was a real question. So we weren’t doing a ton of that in my practice to begin with, and so it didn’t really impact us. The main thing after the ARRIVE trial, I would say, is it really made conversations about induction easier. Because it used to be, I would say, listen, we’re going to induce you. I hope it doesn’t increase your risk of C-section. But even if it does, listen, we really got to do it because of this concern or that concern or this reason or that reason. But now I can tell people, “I think you should be induced”, because of this reason or this reason or this reason. And just so you know, this really should not increase your risk of a C-section. And that makes it much more palatable for people on the receiving end of that kind of counseling.

Emily Oster:

It’s interesting because I do want, when we talk about how this has changed practice, I actually really want to dive into this elective induction. It sounds, from your standpoint, that’s just not something you do much of. That you basically, that’s not a big part of your clinical practice now, or before or after.

Dr. Nathan Fox:

Author So I don’t have a problem with it, and certainly I would be okay doing it, like if someone said “I’m 39 weeks or I’m 40 weeks, and I want to be induced because I’m done”, or whatever it is, I think it’s fine. The problem is from a data standpoint, you can justify it. Again, and you may be able to justify it on everybody. If someone says, “Well, you know, why not induce they don’t have hypertension? Maybe there’s a slightly lower risk of C-section.” I get it. But the problem is practically when you induce someone’s labor, they’re in a labor room for a very long time. And so we just don’t have the space for that. Our labor floor has X amount of labor rooms ,and if the average time of an induction for a first baby is about 18 hours, somewhere between 12 and 24, and so someone’s in a labor room for 12 to 24 hours versus someone who comes in labor on their own and the average time in a room is six hours. You’re going to need three to four times as many rooms to deliver the same number of people.

And so, even if I wanted to induce everyone electively at 39 weeks, my hospital wouldn’t let me. They’d be like, dude, we don’t have room. We can’t do it.” And so, it doesn’t come into play in our practice, and maybe smaller hospitals, which have a lot of space and it doesn’t really make a difference. Yes, potentially, but in our practice it’s just not relevant. Which is also part of the reason, when people are saying… Whenever big studies come out, it’s not the I told you sos, but what happens is a big study comes out and within 15 minutes every expert in every society feels like they have to put this long-winded statement about it, and what is the conclusion? It’s like anything, and it’s frankly kind of annoying. It’s sort of like the race to be better. I’m going to get on this first, I’m going to get on this first, like I got this scoop.

But the problem is people make these recommendations like, “Oh, since it doesn’t increase the risk of C-section and since there was a slightly lower risk and no hypertension, I think everybody should be induced.” It’s like watching SportsCenter and someone’s like, “Oh, we got to trade this guy because they missed a free throw.” And it’s literally the same thing, but people don’t think that through. If we induce everyone, we can’t deliver anybody. We don’t have enough labor rooms in this country to do that. And so, these things have to be much more thoughtful in how to deal with new data.

Emily Oster:

I just want to say that with my second kid, I had the baby 23 minutes after arriving at the hospital, so I feel like I was really efficient in my use of the labor.

Dr. Nathan Fox:

You should get a discount.

Emily Oster:

I should get a discount.

Dr. Nathan Fox:

Like a rebate.

Emily Oster:

I want my baby rebate. All I got was this baby, and it’s no rebates at all.

So I want to talk a little bit about the limitations of the study before we talk about some of this issue about how this changed practice is important, but to talk about the limitations. So I’m interested, I can tell you for me, I think the most significant limitations on this study are, number one, the kind of low-risk women with their first child restriction and the question of whether that applies more broadly. And the second, is that the overall C-section rate in this cohort is really low relative to the US rate overall, and that makes me worried that this did not reflect the broader swath of the US population.

Dr. Nathan Fox:

So you are definitely correct across the board, as you often are. I don’t think that ends up being the biggest issue with this study though, because the low-risk women are the ones who we were most concerned about increasing their risk of C-section. So someone’s young and healthy and fit, and the pregnancy is going great, you’re like, “Hey, you should have the lowest risk of C-section out of anybody”, again amongst people having their first baby. And so the fear is, if I just induce you, maybe I’m going to screw that up and double your risk of C-section, or something like that. And so, I think this study did show that that does not seem to be the case. Meaning if you are young, low-risk, healthy, all these things, it probably does not make a big difference whether you get induced or wait to go into labor on your own.

I agree that you can’t apply these numbers to higher-risk cohorts, but I would retort with two things. Number one, in the higher-risk cohorts, it seems to be the same. If you look at other higher-risk cohorts, it does not seem to increase the risk of C-section. And the only difference is that they may have a higher risk overall, whether they’re get induced or they wait. Meaning of, let’s say, it’s about 10% of the youngest, healthiest of patients, great. And if you take a different cohort, maybe it’s 20% ,and another one it might be 30%, but it does not seem to differ whether you induce them or wait. And that seems to be what the data shows. I think the biggest problem, not problem, but the biggest misinterpretation of this study is that this is what’s going to be everywhere in the country. Because this is, you’re talking about major academic medical centers with lots of resources, 24-hour OB residents and attendings, and anesthesiologists, and a lot of nurses, and they know they’re being studied so they’re doing their inductions very cautiously and patiently, sort of the quote right way.

But if you try to replicate this in every hospital in the US, there’s a lot more pressures. Like I said, what they’re like, “Dude, we are cramped with rooms.”

Emily Oster:

We’re out of labor.

Dr. Nathan Fox:

Yeah. Move it along, section your patient, get her delivered, whatever it is, we got three people waiting for a room. And those are legitimate pressures, and some of them are just doctors practice differently or nurses practice differently, or patients have different desires. Maybe some of them are sort of only half-heartedly in on the induction versus that. And so in practice, those C-section rates are not replicated, but it does not mean that inducing increases the risk ever else. It just means people might not be following the protocol the exact same way they did it.

Emily Oster:

Right. Yeah, I mean I think, in some ways, that’s a little bit of an academic distinction, because from the standpoint of a patient, the question is if I have this induction, will it increase my risk of C-section? And there’s a kind of mechanistic question, which is would it have to as done perfectly? And they think that what this trial says is, no. And then there’s a question of might it in the real world because they’re running out of rooms, and we know that inductions are slower and that you need patience. I don’t know if you’re, somebody told me bring a long book was their main advice. I don’t know if that was you.

Dr. Nathan Fox:

Not until I wrote books, did I ever tell people to bring a book. I tell people bring a charger.

Emily Oster:

Bring an iPad, a charger, and a lot of shows.

Dr. Nathan Fox:

Bring a charger.

Emily Oster:

But I think that is important, because from the standpoint of the patient, if you want to ask the question, “Will being induced increase my risk of C-section”, you do want to think about does the place that I’m doing this have the capacity to wait, have the capacity to have me there for 24 hours? And that’s part of the mechanism and something that doesn’t show up much in the trial for a bunch of reasons.

Dr. Nathan Fox:

I think for people listening, from the patient perspective, if you’re trying to get a sense of how do I know if this applies to me, the simplest way is to ask your doctor or midwife, “What are your inductions like? What happens?” And if, in that process, they say, “We do A, we do B, we do C”, and they say things like, “And we’re very patient because it takes a long time, and we know it takes a long time and we really try to wait as long as we can, as long as it’s safe”, then probably you’re getting an induction that’s very similar to what they did in this study. And probably it’s not increasing your risk of a C-section.

If they say, “You know what? People say inductions don’t increase the risk of C-sections, but I don’t buy it. I don’t know, I’m sectioning everybody by 4:00 or 5:00 PM the next day. 12 hours later, and so I haven’t found that”, then probably you’re getting a less patient form of an induction and maybe it will increase the risk for you. And I think that’s really the best way to sort this out on your own.

Emily Oster:

Yeah. So it’s interesting, if you sort of move now to thinking about this after period, there’s two things to pull out. So one is, actually, there have been some sort of studies post-this, which have less good data. So their data is not as good, it’s not randomized, but have suggested that there is still a relationship between inductions and C-sections. And maybe that is reflective of the same biases in the data before, maybe it’s reflective of some changes, or some of this lack of patience.

But the other thing that comes out, is people will now say, “My doctor told me that they always induce at 39 weeks, that is now standard practice.” Or people will say, “My doctor told me that ACOG recommends that everyone be induced at 39 weeks.” And some people don’t want that. And it was sort of interesting to hear your answer at the beginning about how isn’t you’re practicing, because there is a really, really important distinction between telling a patient there are some reasons to induce, and by the way, there isn’t this downside on the other side, and telling somebody we really, like ACOG is saying, you got to get the baby out or you might have a stillbirth, which is what some of these guys are hearing.

Dr. Nathan Fox:

So ACOG does not say that, for the record. They do not say that you have to-

Emily Oster:

Yes, they don’t say that, but people are hearing from their doctors that ACOG says this.

Dr. Nathan Fox:

Right. No, I agree. I gave a lecture recently, it was called When to Go Rogue, sort of like there’s recommendations out there where they just don’t make sense. And one of the great ones is, if you’re a low-risk uncomplicated pregnancy and you’re seeing one of those doctors who says things like that, up until 38 weeks and six days, you’ll be told you absolutely, positively cannot be induced because it’s dangerous for the baby, it’s not allowed, it’s illegal. I’m going to lose my hospital privileges. And then, when midnight hits and you’re 39 weeks and zero days, you must be induced. It’s absolutely the best thing for you and the baby. Now there is no biologic plausibility to that, zero. It makes no sense. Anyone listening to that would be like, “Well that’s stupid.”

But if you sort look at things as black and white, okay, you could have one study that says, black and white, you shouldn’t be induced before 39 weeks with a reason. And another study that says black and white, you should be induced at 39 weeks, but you have to take everything and all of the data together into context. So I don’t think it’s unreasonable to say, “I think the best strategy is to induce everybody at 39 weeks because it does not increase the risk of C-section”, and because it might lower the risk or lower the risk of that. Okay, but that doesn’t mean it’s the right answer for everyone, because again, there’s logistical issues like we mentioned before. There are patient preference issues. I don’t want to be induced at 39 weeks, I don’t want to have a 24-hour labor. I want to wait and go into labor of my own A, so it’s shorter, B, because I think it’ll make my chance of needing an epidural lower, or C, because it’ll just make me feel more in touch with, whatever the reason is.

Those are all quite reasonable thought processes. And unless there’s some reason not to wait past 39 weeks, that should be an option. So what I tell people typically is any time between 39 and 41 weeks, and maybe for some people 42 weeks, is a reasonable time to be induced. And there’s benefits to going earlier, towards 39 weeks, and there’s benefits to waiting longer, towards 41 weeks. And unless there’s a real medical issue at hand, no one could say that one benefits are better than the other benefits.

And so I tell people, typically, again, unless there’s a reason to deliver earlier or for a specific time, I’m very comfortable 39 to 41 weeks. If you’re someone who wants to be done as soon as humanly possible, you don’t feel well, you’ve got people coming in town, whatever it is, you want to be delivered at 39 weeks, I’ll say, “Fine, if we can get a room. Just be prepared for long induction, God bless.” And if they want to wait till 41 weeks, the downside is well, you’re pregnant for two weeks more, you may not go into labor and you may end up with an induction anyways, and there’s small risks to you and to the baby, very slight. I don’t try to scare people or anything, but they are, there’s very small risks of waiting longer in pregnancy. And that’s it. And most people will tell you what they want, most people will show you their cards. It’s not that hard.

Emily Oster:

Yeah. And I think giving people the space to talk about their preferences and talk about their preferences for their birth, which people have-

Dr. Nathan Fox:

They should.

Emily Oster:

When I was pregnant, I really wanted to go into labor without an induction. I did not want to have an epidural. I think it’s pretty clear from the data that an induction increases the pain associated with parts of labor, and people are more likely to have epidurals probably for a bunch of reasons. I

Dr. Nathan Fox:

It increases the duration. The pound for pound, the contractions, I’m told, are the same.

Emily Oster:

Pound for pound, you think it’s the same?

Dr. Nathan Fox:

Well they are. I’ve never had an induction or a contraction, but I think the data is that the actual contractions don’t hurt more. The difference is you basically start, you slam on the gas at the very beginning versus a very slow uptick to get into labor.

Emily Oster:

To ramp it.

Dr. Nathan Fox:

Yeah.

Emily Oster:

But for me, it important to avoid an induction, or at least do what I could. And I think those preferences have value and people differ in what their preferences are there, and that’s important. That’s something we need to be thinking about.

Dr. Nathan Fox:

A hundred percent. Listen, this is one of the great sort of, not secrets, but one of the real arts in medicine, and just as a plug, we do discuss this in the book. That on the one hand, what’s my job as a doctor and is it to just tell you what’s right and tell you what to do? Or is it for me to just discuss all the options, lay them out on the table and let you choose, like you were at a restaurant choosing from a menu. And I would argue it’s really neither of those, it’s in between. It’s to have a conversation with you about what I think are sort of reasonable brackets to put around your options. And for me to tell you, I think this is a bad option because of this. If you’re going to make a bad choice, if you said, “I don’t want to be induced because I don’t want to get an epidural and I want to go until I’m 43 weeks pregnant”, I would’ve said to you, “I think you’re making a mistake.”

Obviously, I can’t force you to be induced, but I would be firm. I would say, “I think you’re making a mistake. Here is why.” And I would explain the reason why. But if you’re within a timeframe that I think is reasonable, like you said, well, I don’t want to be induced at 39 weeks, I want to wait until as close to possible as 41 weeks or go a little bit past, then my job is talk to you about the pluses and minuses and then let you make a choice. And that’s reasonable. And I think that a lot of either patients want something different ,or a lot of doctors do something different, where they’re on the one hand either too dogmatic and they just give people black and white, or they can’t make up their damn mind and people are left with like, “Well, you’re the doctor, what do you think?” Some people just won’t give an opinion, which I think is also a mistake.

Emily Oster:

Yeah. No, it’s interesting. I mean it feels like such a balance, a hard balance for a practitioner to be kind of simultaneously the menu, but an expertly curated menu. There’s a lot of things on here you can have, but let me just tell you, the oysters aren’t that great today, but we do have those.

Dr. Nathan Fox:

But that’s really true. And it’s also not sometimes as preference, it’s if I said, “Well, I mean think of it more this way. You’re allergic to nuts, don’t eat these four things”, or you’re gluten-free, don’t eat these six things, or you said you don’t like this spice, don’t have this. Meaning it’s more than just giving someone advice, although there is some of that. It’s really about saying, “Okay, this preference of yours is reasonable and safe”, even if it’s not, let’s say, typical, whatever. Whereas this one is really just not a safe idea and here’s why. And to be able to articulate that, is also not easy because sometimes it’s just easier to say, “Let’s do this.” And all right, and that some people are okay with that, but many people are not.

Emily Oster:

Nate, you’ve talked a couple of times about the possible benefits of induction, or the possible dangers of waiting longer, can you just say a little bit more about what those are?

Dr. Nathan Fox:

Yeah, I mean if you take someone who’s 39 weeks and low-risk, there’s no issues going on, and you deliver the baby on that day, whether it’s a C-section, whether it’s induction, whatever it is, the outcomes for the baby are as good or better than if waiting. Meaning there isn’t an increased risk of prematurity or delivering before it’s time, or anything like that. Whereas earlier in pregnancy, that’s always a concern. So once you get to 39 weeks, you don’t really have that benefit to the baby of waiting longer, letting the baby develop further, grow further, things like that. And so, that upside is kind of done at 39 weeks, but there is a downside of waiting, and it’s hard to talk about because it’s terrifying and it’s also very rare, and that’s the risk of stillbirth. A perfectly healthy pregnancy can end up having a baby that passes away inside after 39 weeks.

It could happen at any point in pregnancy, but that risk is present if you’re still pregnant, and it’s absent if you’ve delivered. And so even though that risk is very, very small, fortunately, well less than 1%, it is on the table. And so for some people, they’re like, “Listen, everything’s good today, I want the baby out.” And again, that’s not unreasonable. It’s not a recommendation because the likelihood of something bad happening between 39 and 41 weeks is so low, especially if someone is monitoring how the baby’s moving or they come to the office, they have a test, whatever it is that they’re getting prenatal care in some capacity. The chance is so, so low that it’s not recommended that everybody has to be induced, but it is a potential risk.

And so for that reason, some people are more adamant about delivering at 39 weeks, just to make that minuscule risk a more minuscule risk. There’s also a risk of developing hypertension as you move on in pregnancy, like gestational hypertension, preeclampsia, that does not tend to be a life-threatening thing for the mother or baby if it’s, again, followed and watched and treated, and all these things. So the bigger driving force tends to be that possibility of stillbirth versus you’re not increasing the risk to the baby after birth, of things like prematurity.

Emily Oster:

And this is just to touch on this, because it’s something we talk a little bit about in the book, but your prior experiences with pregnancies sometimes play into this choice. So if someone has had a stillbirth, or even a pregnancy loss earlier, sometimes those risks, even if they are in practice very small, can loom much larger. And so that is a reason why it could make sense for somebody to induce at 39 weeks, if that’s a present risk in their minds, even if it is not something that is medically a higher risk.

Dr. Nathan Fox:

Right. Or sometimes, I mean even earlier potentially, someone has a history of a stillbirth, frequently we deliver them before 39 weeks, and we take that extra risk, after birth, of the baby being slightly less mature. I mean, at 37 or 38 weeks, the risks aren’t huge, but okay, we’ll sometimes take that risk because number one, the anxiety over waiting is so great, understandably, for these women. I mean it’s awful, the anxiety that they’re having at that point. And since we’re humble enough to know we don’t know everything about everything, and I couldn’t possibly tell someone, “Oh, because your stillbirth happened for X reason, there’s no chance it’s going to happen again this pregnancy.” That would be a lot of hubris for me to say that. And so sometimes even earlier.

But yes, people’s own fears and anxiety, sometimes it’s a cousin of mine had a stillbirth, right? So if a cousin of mine had a stillbirth, I’m not at increased risk of having a stillbirth, but it’s on my mind a lot more than someone who’s never really had that in their world, thank God. And so, people’s anxieties in general definitely play into that decision about when they want to deliver. I would say, for most people, it’s not pressing in their mind, fortunately. That would be very daunting to be pregnant if it’s always pressing in someone’s mind, but occasionally is, but that is sort of the risk, the unspoken risk, that people try not to say out loud too much. Because once you drop stillbirth during a prenatal visit, it changes everything afterwards. It’s very hard to talk about it but not talk about it at the same time.

Emily Oster:

Yeah. All right, so to bring it back to the ARRIVE trial, and we think about takeaways, I think the biggest takeaways for me here, and then I’m going to let you give your big takeaways, if they disagree, are-

Dr. Nathan Fox:

Foreshadowing the book.

Emily Oster:

Number one, this is a really good trial, and that in general based on, and this is the best evidence we have, and it does not suggest that an induction needs to lead to an increased risk of C-section. But my second takeaway is that it also doesn’t mean that you have to have an induction at 39 weeks, and that it’s worth asking. I mean, this is really your point, so I’m stealing it because I got to go first. But that it is worth talking to your provider about, really, their ability to be patient is the biggest thing I would put out there, their ability to let the induction take a long time.

Dr. Nathan Fox:

Yeah, I mean my takeaways, obviously I agree with all three. I would say that one of the important aspects about induction is asking, “Why are you recommending this?” Right? Are you recommending it just because I’m 39 weeks and I’ve hit a certain number, but everything is going perfectly fine, in which case I think there’s a lot of room for waiting and pushback, like maybe I don’t want to induce, versus are you recommending it because you have a specific concern for me or my baby about waiting on top of just the, I’m getting more pregnant? Meaning is it because I’m 45 years old and you’re worried about a risk of a stillbirth? Is it because I have diabetes and you’re worried about a risk of a stillbirth? Is it because my blood pressure’s creeping up and you’re worried about me getting severe hypertension? That’s a very different reasoning than just because. I think having a conversation, like you mentioned, that I mentioned, about the ability to be patient, but also even more generic than that, just tell me what an induction is like with you or at your hospital.

And again, just like patients will tell you what they think, doctors and midwives will tell you what they think. We’re not secretive. Our personalities come out, our opinions come out, and you want to get a sense. Ideally, these conversations should happen early in pregnancy, not specifically about induction, but just in general, because you’ll get a sense, is this a person I trust. And if it’s a person I trust, then probably this conversation will be very easy because you’ll already have that rapport. If you’re not sure if you trust this person, that’s not a good place to be.

Emily Oster:

I wish I had had that advice with my first pregnancy because I remember getting to the end and telling the doctor, “I’m planning not to have an epidural.” And they were like, “Oh, yeah, we’ll see how that goes.”

Dr. Nathan Fox:

Good luck with that.

Emily Oster:

And I was like, “Oh, we should have touched on this earlier.”

Dr. Nathan Fox:

Yeah, but it’s interesting. I mean, I tell people that get epidurals, don’t epidural. God bless, whatever you want is fine. It is true that, at least in our hospital, 90% of women get epidurals. That’s just sort of the numbers, but I don’t… God bless, if you’re going to be in the 10%, I think that’s awesome. As I say, your labor won’t hurt me one bit, so whatever works, great. I think it’s terrific. There are a few exceptions when I may push someone into an epidural, but I mean twins, sort of rare exceptions. But it’s more important, I mean things like we discuss that attitudes in general about induction. If someone has a rule that they induce all their patients at 39 weeks, that’s something that probably should be told upfront at the beginning of pregnancy when you join, because that’s not what’s recommended. It’s fine, it’s not unreasonable, but it’s not the only way to do it. And it’s not what ACOG says. We don’t do it. We don’t induce everyone at 39 weeks, and we seem to have not been arrested.

Emily Oster:

Nate, I love to talk to you. I can’t wait to talk to you more. We’ll do more stuff with our new book, and it’s always just a treat.

Dr. Nathan Fox:

Love it. Thanks for having me. Thanks for bringing me into your world. It’s been a wild ride, and it’s awesome.


Emily Oster:

Parent Data is produced by Tamar Avishai with support from the parent data team and PRX. Also special thanks to our house violinist, my daughter Penelope.

Penelope:

No problem Mom.

Emily Oster:

If you have thoughts on this episode, please join the conversation on my Instagram @ProfEmilyOster. And if you want to support the show, become a subscriber to the Parent Data Newsletter at pdstaging24.wpenginepowered.com, where I write weekly posts on everything to do with parents and data to help you make better, more informed parenting decisions. For example, in April, 2020, I wrote a post going into the ARRIVE trial in much more detail. If you like what you hear, please leave the show a positive review on Apple Podcasts. It really helps people find out about us. Right Penelope?

Penelope:

Right Mom.

Emily Oster:

We’ll see you next time.

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