Emily Oster

10 min Read Emily Oster

Emily Oster

Labor Induction and C-Section

The facts behind the "cascade of interventions"

Emily Oster

10 min Read

What is the relationship between induced labor and having a C-section? This is one of the most common questions I get — once, someone ran after me on the street in New York to ask about it — and it’s not hard to see why. The share of induced labors has gone up over time, and many pregnant women will be offered, or pushed towards, a labor induction at or around 39 weeks of pregnancy.

Choosing labor induction often goes along with medical advice. On the flip side, though, there is a common concern that labor induction might decrease the chance of having a vaginal birth. The narrative is that labor induction is just the first part of a “cascade of interventions” that are more likely to lead to a C-section. C-sections are extremely safe, and can be literally lifesaving, but for many women they aren’t the preferred mode of delivery. The possible link with inductions may give pause.

So which is it? Do elective labor inductions make a C-section more likely?

There is a simple data-based answer to this, which is to cite the one large randomized trial on the topic. That trial suggests that, no, elective labor induction doesn’t lead to more C-sections. But this answer is incomplete. It doesn’t grapple with why other data might show something else, and it also doesn’t get to where this trial might have limitations. I’ll try to give a bit more of a complete picture today.

It’s easiest to start, though, with the randomized trial.

The ARRIVE trial

The best evidence we have on the link between induction and the rate of C-section (and other outcomes) comes from the ARRIVE trial. I’ve written about it before, in Expecting Better and also in this newsletter in 2020. The reason that this is our best data is that it’s a well-run randomized trial. The study recruited about 6,000 low-risk women in their first pregnancies. They were randomly allocated to two groups. In the “induction” group, women were encouraged to induce labor at 39 weeks. In the “expectant management” group, women were encouraged to either wait to go into labor on their own, or induce later if not (typically at 41 weeks).

Although the groups were only encouraged, not forced, in practice the induction group was more likely to be induced than the expectant management group. And because the allocation was randomized, there were no other reasons to expect the two groups to differ in their outcomes.

The researchers looked in the trial for any differences in the labor and delivery experience and any differences in the outcomes for infants. What they found was that there were no notable differences in the outcomes for infants — nothing significantly different across the two groups. This wasn’t a surprise. What was more surprising was they found a lower C-section rate in the induction group than in the other (18% versus 22%). This difference was small in magnitude, but it was surprising in part due to the initial concern that induction would lead to higher C-section rates.

This trial was very compelling, and it caused a lot of practitioners to change their thinking about induction, and what they did in practice. But there is lingering confusion. Most notably: If this trial is right, how do we make sense of so much other evidence showing that C-section rates are significantly higher in women who have induced labor? To answer that, we need to dive into those studies in more detail.

Non-randomized evidence

There are many, many non-random studies on this. I’m going to discuss just two, since I think they illustrate the basic points.

We can start with this paper, published in 2021 in the European Journal of Obstetrics & Gynecology and Reproductive Biology. The paper explores the relationship between induction and C-section in a sample of about 6,000 women at a hospital in Illinois. Using data from the hospital, the authors compare the C-section rate for women whose labor was induced with those who went into labor spontaneously.

The paper finds that at all gestational ages, the share of women who had a C-section was about 16 percentage points higher in the induced group than in the spontaneous labor group. This is a large and highly significant increase, as the authors note.

The problem is that it’s very difficult to attribute this to a causal effect of the induction, for at least two reasons. First, in many cases labor induction occurs because someone has a higher-risk pregnancy. Higher-risk pregnancies are more likely to have a C-section, independent of induction, and it’s hard to fully control for that factor.

Second, and probably more important here, the basic comparison is flawed. They are comparing C-section rates for women who are induced with those who show up already in labor. The fact that this latter group has already gone into labor, and progressed to at least some extent, effectively tells you something about their ability to “successfully” labor.

Put differently: the policy question we want to ask is whether the C-section rate would be higher if everyone were induced at 39 weeks rather than waiting and either be allowed to go into labor on their own or induced later if they did not.* This paper, instead, asks whether the C-section rate would be lower if everyone just went into labor on their own. The answer is almost certainly yes. But that’s not a policy! Whether people start labor on their own is not something over which we have control.

This study is inherently quite flawed. But observational data isn’t all inherently problematic, and better analyses lead to conclusions that echo the randomized trial evidence. For example, there is this study, which analyzed records of about 55,000 women over a period of five years at 21 hospitals in the northwestern U.S.

This study takes a different approach from the one above. Instead of comparing inductions with people who are in spontaneous labor, it compares women who are induced with those who continue their pregnancy. That is: take two women who are 39 weeks pregnant. One has an elective induction, one continues the pregnancy. In the end, how do the C-section rates compare?

The choice still isn’t random, but this analysis is much closer to the policy question we want to answer. In this case, the results echo the randomized trial. The C-section rate is about 15% in the induction group, 23% in the non-induction group. On the flip side, the authors find that the rate of instrument-assisted delivery (that’s delivery with forceps or a vacuum extractor) is higher in the induction group. Overall, the C-section result in particular echoes the randomized trial. And with a larger sample size and better design, this is a much more compelling study.

When we look at the broader swath of this literature, these papers are representative. It’s certainly possible to find studies that show a link between induction and C-section, but they tend to be those that do these more biased comparisons. Better data is more supportive of the randomized trial conclusions.

So … induction doesn’t lead to C-sections?

As implemented in the ARRIVE trial and comparable studies, it seems not.

Which brings us to the big uncertainty, which is whether the real world echoes the trials. Research trials like ARRIVE tend to be run in advanced medical centers, places that may differ in many ways from typical hospitals. Beyond this, the hospitals and their doctors know they are in the trial. It’s possible that this knowledge could impact their behavior (this is called the Hawthorne effect). If behaviors differ in other locations — or, rather, if the effect of inductions on C-sections is different — then the results from the trial may not be applicable everywhere.

This is always a concern in applying randomized trial results to the overall population. We sometimes frame it as a problem of “external validity” of the trial results. For the ARRIVE trial specifically, there are two things in the trial that critics have worried about. One is that the women in the trial are all low-risk women who haven’t had children before, and results could differ for others. The second issue is that the overall C-section rate in the trial is fairly low in both groups. This could point to something different about this context. The fact that the results of the trial are reflected in the larger non-randomized studies is encouraging, and perhaps downplays these concerns. But it’s impossible to fully dismiss them.

In reflecting on this and talking to others, what comes out most frequently in the discussion is the possible role of patience. Labor induction takes time. This is true of all labor, but induction in particular. It can be very slow to get going and slow to progress. Someone told me, “I tell my patients: bring a long book.”

This slowness, or the reaction to it, may influence the relationship between induction and C-section. If practitioners, or their patients, are impatient, they may react to a long labor by moving to a C-section. If induced labor is slower than spontaneous labor, this may happen more in that group. And it might be that this factor is less important in a trial like this one, where everyone is aware of what is being studied, and perhaps thinking through the decisions.

A lot of the discussion around inductions and C-sections is focused on the general feeling that C-section rates are too high. In reality, it may be the case that this impatience — in induced or spontaneous labor — could be a bigger key. We get a nice picture of this from a 2018 paper that studied what happened at one hospital when it changed the guidelines for how it defined a stalled labor.

The new guidelines effectively allowed for a slower progression of labor before a conclusion that a C-section might be necessary. And in response, the hospital saw a 30% decrease in its C-section rate. There’s nothing here specifically about induction — these new policies applied across the board — but this provides a good clue (at least to me) that patience is really key.

Should I be induced?

This entire post is focused on the research question of whether inductions increase the risk of a C-section. The answer to this is one input to the decision of whether or not to have one, but it is not the only one. An induction changes the experience of labor. It isn’t something that everyone wants. If the birth experience you want involves starting labor at home, that’s an important consideration too.

Like with many decisions, data is an input — and this data is reassuring if an induction is the direction you want to go — but only one input. These decisions should be made together between patients and doctors. Armed with data, but also with preferences.


*I use “policy” here loosely — no one is expecting there to be some government policy on labor induction. This is a hospital policy or an obstetrics practice policy.

A chart to help readers decide whether spontaneous labor or induction is the right choice for them.
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The list of what not to do while pregnant feels longer than a CVS receipt. At ParentData, we want to empower you to make the right decisions for you. 

What an amazing group of women, and an honor to speak at the #MomsFirstSummit debunking parenting myths. 

What are some pregnancy rules you chose to bend after being empowered by data?

#emilyoster #parentdata #pregnancyproblems #pregnancymyths

The list of what not to do while pregnant feels longer than a CVS receipt. At ParentData, we want to empower you to make the right decisions for you.

What an amazing group of women, and an honor to speak at the #MomsFirstSummit debunking parenting myths.

What are some pregnancy rules you chose to bend after being empowered by data?

#emilyoster #parentdata #pregnancyproblems #pregnancymyths
...

Looking for Memorial Day Weekend plans? Might be the perfect time to give potty training a shot. Potty training is notoriously difficult, and we unfortunately don’t have a lot of evidence-based guidance on what works best. So I asked the ParentData community to fill out a survey and share their knowledge — about 6,000 people responded.

👉Comment “Link” for a DM to an article that summarizes all of the best potty training advice we collected. 

Remember, you are not alone in the potty training struggle! It can be incredibly challenging, so please give yourself some grace.

#emilyoster #parentdata #pottytraining #pottytrainingtips #toddlertips

Looking for Memorial Day Weekend plans? Might be the perfect time to give potty training a shot. Potty training is notoriously difficult, and we unfortunately don’t have a lot of evidence-based guidance on what works best. So I asked the ParentData community to fill out a survey and share their knowledge — about 6,000 people responded.

👉Comment “Link” for a DM to an article that summarizes all of the best potty training advice we collected.

Remember, you are not alone in the potty training struggle! It can be incredibly challenging, so please give yourself some grace.

#emilyoster #parentdata #pottytraining #pottytrainingtips #toddlertips
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We’re hiring an Associate Editor at ParentData! More details at my link in bio. Please share with the great writers and data-loving people in your network. 📊💻

We’re hiring an Associate Editor at ParentData! More details at my link in bio. Please share with the great writers and data-loving people in your network. 📊💻 ...

Do you brand things a certain way to get your kid to accept it? Like calling carrots “rabbit popsicles”? Or telling them to put on their “super speed socks” in the morning? Share your rebrands in the comments below! You never know who you might be helping out 👇

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Do you brand things a certain way to get your kid to accept it? Like calling carrots “rabbit popsicles”? Or telling them to put on their “super speed socks” in the morning? Share your rebrands in the comments below! You never know who you might be helping out 👇

#emilyoster #funnytweets #relatabletweets #parentingjokes #kidssaythedarndestthings
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Have you ever panic-googled a parenting question when everyone else is asleep? If so, you’re not alone. 

Today is the first episode of a new biweekly series on my podcast: Late-Night Panic Google. On these mini-episodes, you’ll hear from some familiar names about the questions keeping them up at night, and how data can help. First up: @claireholt!

Listen and subscribe to ParentData with Emily Oster in your favorite podcast app 🎧

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Have you ever panic-googled a parenting question when everyone else is asleep? If so, you’re not alone.

Today is the first episode of a new biweekly series on my podcast: Late-Night Panic Google. On these mini-episodes, you’ll hear from some familiar names about the questions keeping them up at night, and how data can help. First up: @claireholt!

Listen and subscribe to ParentData with Emily Oster in your favorite podcast app 🎧

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Sun safety is a must for all ages, especially babies! Here are my tips for keeping your littlest ones protected in the sunshine:
☀️ Most importantly, limit their time out in hot weather. (They get hotter than you do!)
☀️ Keep them in the shade as much as possible when you’re out.
☀️ Long-sleeve but lightweight clothing is your friend, especially on the beach, where even in the shade you can get sunlight reflecting off different surfaces.
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Comment “Link” for a DM to an article on the data around sun and heat exposure for babies.

#sunsafety #babysunscreen #babyhealth #parentdata #emilyoster

Sun safety is a must for all ages, especially babies! Here are my tips for keeping your littlest ones protected in the sunshine:
☀️ Most importantly, limit their time out in hot weather. (They get hotter than you do!)
☀️ Keep them in the shade as much as possible when you’re out.
☀️ Long-sleeve but lightweight clothing is your friend, especially on the beach, where even in the shade you can get sunlight reflecting off different surfaces.
☀️ If you want to add a little sunscreen on their hands and feet? Go for it! But be mindful as baby skin tends to more prone to irritation.

Comment “Link” for a DM to an article on the data around sun and heat exposure for babies.

#sunsafety #babysunscreen #babyhealth #parentdata #emilyoster
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I’m calling on you today to share your story. I know that many of you have experienced complications during pregnancy, birth, or postpartum. It’s not something we want to talk about, but it’s important that we do. Not just for awareness, but to help people going through it feel a little less alone.

That’s why I’m asking you to post a story, photo, or reel this week with #MyUnexpectedStory and tag me. I’ll re-share as many as I can to amplify. Let’s fill our feeds with these important stories and lift each other up. Our voices can create change. And your story matters. 💙

#theunexpected #emilyoster #pregnancycomplications #pregnancystory

I’m calling on you today to share your story. I know that many of you have experienced complications during pregnancy, birth, or postpartum. It’s not something we want to talk about, but it’s important that we do. Not just for awareness, but to help people going through it feel a little less alone.

That’s why I’m asking you to post a story, photo, or reel this week with #MyUnexpectedStory and tag me. I’ll re-share as many as I can to amplify. Let’s fill our feeds with these important stories and lift each other up. Our voices can create change. And your story matters. 💙

#theunexpected #emilyoster #pregnancycomplications #pregnancystory
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OUT NOW: My new book “The Unexpected: Navigating Pregnancy During and After Complications” is available on April 30th. All of my other books came out of my own experiences. I wrote them to answer questions I had, as a pregnant woman and then as a new parent. “The Unexpected” is a book not to answer my own questions but to answer yours. Specifically, to answer the thousands of questions I’ve gotten over the past decade from people whose pregnancies were more complicated than they had expected. This is for you. 💛 Order now at my link in bio!

OUT NOW: My new book “The Unexpected: Navigating Pregnancy During and After Complications” is available on April 30th. All of my other books came out of my own experiences. I wrote them to answer questions I had, as a pregnant woman and then as a new parent. “The Unexpected” is a book not to answer my own questions but to answer yours. Specifically, to answer the thousands of questions I’ve gotten over the past decade from people whose pregnancies were more complicated than they had expected. This is for you. 💛 Order now at my link in bio! ...

OUT NOW: My new book “The Unexpected: Navigating Pregnancy During and After Complications” is available on April 30th. All of my other books came out of my own experiences. I wrote them to answer questions I had, as a pregnant woman and then as a new parent. “The Unexpected” is a book not to answer my own questions but to answer yours. Specifically, to answer the thousands of questions I’ve gotten over the past decade from people whose pregnancies were more complicated than they had expected. This is for you. 💛 Order now at my link in bio!

OUT NOW: My new book “The Unexpected: Navigating Pregnancy During and After Complications” is available on April 30th. All of my other books came out of my own experiences. I wrote them to answer questions I had, as a pregnant woman and then as a new parent. “The Unexpected” is a book not to answer my own questions but to answer yours. Specifically, to answer the thousands of questions I’ve gotten over the past decade from people whose pregnancies were more complicated than they had expected. This is for you. 💛 Order now at my link in bio! ...

OUT NOW: My new book “The Unexpected: Navigating Pregnancy During and After Complications” is available on April 30th. All of my other books came out of my own experiences. I wrote them to answer questions I had, as a pregnant woman and then as a new parent. “The Unexpected” is a book not to answer my own questions but to answer yours. Specifically, to answer the thousands of questions I’ve gotten over the past decade from people whose pregnancies were more complicated than they had expected. This is for you. 💛 Order now at my link in bio!

OUT NOW: My new book “The Unexpected: Navigating Pregnancy During and After Complications” is available on April 30th. All of my other books came out of my own experiences. I wrote them to answer questions I had, as a pregnant woman and then as a new parent. “The Unexpected” is a book not to answer my own questions but to answer yours. Specifically, to answer the thousands of questions I’ve gotten over the past decade from people whose pregnancies were more complicated than they had expected. This is for you. 💛 Order now at my link in bio! ...

Is side sleeping important during pregnancy? Comment “Link” for a DM to an article on whether sleep position affects pregnancy outcomes.

Being pregnant makes you tired, and as time goes by, it gets increasingly hard to get comfortable. You were probably instructed to sleep on your side and not your back, but it turns out that advice is not based on very good data.

We now have much better data on this, and the bulk of the evidence seems to reject the link between sleep position and stillbirth or other negative outcomes. So go ahead and get some sleep however you are most comfortable. 💤

Sources:
📖 #ExpectingBetter pp. 160-163
📈 Robert M. Silver et al., “Prospective Evaluation of Maternal Sleep Position Through 30 Weeks of Gestation and Adverse Pregnancy Outcomes,” Obstetrics and Gynecology 134, no. 4 (2019): 667–76. 

#emilyoster #pregnancy #pregnancytips #sleepingposition #pregnantlife

Is side sleeping important during pregnancy? Comment “Link” for a DM to an article on whether sleep position affects pregnancy outcomes.

Being pregnant makes you tired, and as time goes by, it gets increasingly hard to get comfortable. You were probably instructed to sleep on your side and not your back, but it turns out that advice is not based on very good data.

We now have much better data on this, and the bulk of the evidence seems to reject the link between sleep position and stillbirth or other negative outcomes. So go ahead and get some sleep however you are most comfortable. 💤

Sources:
📖 #ExpectingBetter pp. 160-163
📈 Robert M. Silver et al., “Prospective Evaluation of Maternal Sleep Position Through 30 Weeks of Gestation and Adverse Pregnancy Outcomes,” Obstetrics and Gynecology 134, no. 4 (2019): 667–76.

#emilyoster #pregnancy #pregnancytips #sleepingposition #pregnantlife
...

My new book, “The Unexpected: Navigating Pregnancy During and After Complications” is available for preorder at the link in my bio!

I co-wrote #TheUnexpected with my friend and maternal fetal medicine specialist, Dr. Nathan Fox. The unfortunate reality is that about half of pregnancies include complications such as preeclampsia, miscarriage, preterm birth, and postpartum depression. Because these are things not talked about enough, it can not only be an isolating experience, but it can also make treatment harder to access.

The book lays out the data on recurrence and delves into treatment options shown to lower risk for these conditions in subsequent pregnancies. It also guides you through how to have productive conversations and make shared decisions with your doctor. I hope none of you need this book, but if you do, it’ll be here for you 💛

#pregnancy #pregnancycomplications #pregnancyjourney #preeclampsiaawareness #postpartumjourney #emilyoster

My new book, “The Unexpected: Navigating Pregnancy During and After Complications” is available for preorder at the link in my bio!

I co-wrote #TheUnexpected with my friend and maternal fetal medicine specialist, Dr. Nathan Fox. The unfortunate reality is that about half of pregnancies include complications such as preeclampsia, miscarriage, preterm birth, and postpartum depression. Because these are things not talked about enough, it can not only be an isolating experience, but it can also make treatment harder to access.

The book lays out the data on recurrence and delves into treatment options shown to lower risk for these conditions in subsequent pregnancies. It also guides you through how to have productive conversations and make shared decisions with your doctor. I hope none of you need this book, but if you do, it’ll be here for you 💛

#pregnancy #pregnancycomplications #pregnancyjourney #preeclampsiaawareness #postpartumjourney #emilyoster
...

We are better writers than influencers, I promise. Thanks to our kids for filming our unboxing videos. People make this look way too easy. 

Only two weeks until our book “The Unexpected” is here! Preorder at the link in my bio. 💙

We are better writers than influencers, I promise. Thanks to our kids for filming our unboxing videos. People make this look way too easy.

Only two weeks until our book “The Unexpected” is here! Preorder at the link in my bio. 💙
...