The Complicated Truth About C-sections
By: Emily Oster
Tags: C Section, Body, Health, Pregnancy, Birth

The Complicated Truth About C-sections

Your friends and the internet are not the best source for up-to-date information

Credit: Tetra Images/Brand X Pictures/Getty

When I was pregnant with my first child — my daughter — I embraced the assumption that, if at all possible, it’s best to avoid having a Cesarean section. I made a lot of choices which I believed were in the service of trying to avoid one, including not having a potentially labor-extending epidural. And I was lucky in that, in this particular domain anyway, things went according to plan.

The history of the Cesarean section is rooted in myth and ancient storytelling. While the backstory is tough to untangle, C-sections are thought to have been performed for millennia, with the earliest procedures attempted on dying mothers in hopes of saving their infants. It’s believed that the first “successful” Cesarean — where both the mother and infant survived — was performed by a pig gelder named Jacob Nufer in the 1500s, though historians question the veracity of this story.

What is certain is that the reliable and consistent use of the C-section came hundreds of years later. It took improvements in wound management and the creation of better antibiotics before the Cesarean became a medical mainstay. But in making up for lost time, C-sections are now both common and routine. Roughly 30 percent of births in the U.S. are performed this way, and the figures are even higher elsewhere: In China, only about half of births are vaginal.

It’s become fashionable of late, at least in the U.S., to malign this high C-section rate and argue that we must decrease the number performed through better doctor and patient education and less continuous fetal monitoring. But this argument hinges on the presumption that it is best to avoid having a C-section, if you can.

Several years ago, inspired equally by my pregnancy and my love of data, I wrote a book — Expecting Better — that used statistical evidence to help women and their partners make better decisions while expecting. In the case of C-sections, I took my assumptions and the received wisdom, effectively, for granted. I dismissed the Cesarean as something every woman would like to avoid, if at all possible.

This approach didn’t sit well with everyone. I received emails from women who underwent emergency C-sections and were now panicked. They heard that C-sections were terrible for children’s health and development, even leading to long-term disease. Should they have tried harder? Was there anything they could do now?

I also received a surprising number of emails from women wondering whether the push against C-sections was just another overreaction, not backed by evidence. “Doesn’t [a C-section] just seem simpler?” they’d write. “Why should I risk the uncertainty of a vaginal birth?”

The share of women who actually have elective C-sections is thought to be small — perhaps 3 percent of births — and it is hard to know if it has increased over time, or if it just seems that way based on media attention and my inbox. What has changed is that in 2013 the American Congress of Obstetricians and Gynecologists issued an opinion suggesting that elective Cesareans could be a viable choice, in some cases.

So, what’s the truth? Is having a C-section an outcome to be mourned and avoided at all costs? Or is it the simpler, less uncertain option? Maybe it’s even an option to be (whispers) sought out? I decided to revisit this part of the book with an open mind, and dove back into the data.

Such questions cannot be answered based on friends’ anecdotes, nor via internet search; though the need for data does not completely trump the value of personal experience. From anecdotes, we can infer that there’s lots of variation in women’s birth experiences and recovery. With a vaginal birth, you could be like Kate Middleton — on the steps of the hospital in full hair and makeup five hours later — or you could have a fourth degree vaginal tear that takes months to heal. Some women are up and about a day or two after a C-section; others take weeks to pick up their baby without pain.

But this uncertainty shouldn’t get in the way of decision-making, even as we keep it in mind. To make the right choices, we have to interrogate the data, even if it comes with noise.

Is having a C-section an outcome to be mourned and avoided at all costs? Or is it the simpler, less uncertain option?

When I study questions like this, there are two kinds of data I look for. The first, and the gold standard, is a randomized controlled trial, or RCT. In the textbook example of this kind of study, researchers would take a group of women and randomly select some to have a C-section and some to have a vaginal birth, and then compare the results.

As you can probably imagine, this raises some ethical concerns and, indeed, there is only one study from the late 1990s that comes close to meeting these standards, and it focused on breech (i.e. not head down) deliveries. It’s useful, but limited in scope and outcomes.

For the most part, then, our conclusions rely on “observational” studies, which look at the outcomes of women and their babies following a C-section and compare them to those who had a vaginal birth. These studies can be very large, and they have the advantage of allowing us to look at a wide range of outcomes. One study example, published in 2015, includes over 300,000 births in Scotland from 1993–2007 and links delivery method to many long-term health issues for children.

The problem, of course — or, better put, the caution — with these studies is that women who have C-sections tend to be different in other ways. For example, women who are obese before pregnancy are more likely to deliver by C-section. Child obesity has been linked to C-section birth, but we know that maternal and child obesity are also closely linked. It’s challenging to separate these effects.

With all that in mind, let’s get to the question: What are the risks or benefits of C-sections?

How Do C-sections Impact Maternal Recovery?

Let’s start with the recovery process for the mother. Here, there’s good news and some bad news.

C-section recovery is generally a slower process for obvious reasons. A C-section is major abdominal surgery; walking around will typically take a few days, and any physical activity — including standing, rolling over, or taking the stairs — will be painful for a while, perhaps several weeks.

Vaginal birth can also be traumatic, and recovery can be long, but on average it’s shorter. In principle, you can typically walk around a few hours later. The lingering consequences are mostly vaginal — not to downplay these — and have less impact on your everyday life activities.

I had a vaginal birth with my daughter, and our first activity after arriving home was to take a walk outside. A close friend had a C-section around the same time, and the first thing she did was order a second changing table so she could have one on every floor of the house because she couldn’t manage the stairs.

The good news is, if we look at one or two years after birth, there is no evidence of differences in recovery. If anything, the data might slightly favor C-sections.

In a 2018 meta-analysis of 80 studies, including 30 million people, researchers looked at a number of outcomes for mothers, including urinary incontinence, fecal incontinence, pelvic organ prolapse, pelvic pain, and the incidence of painful sexual intercourse. For most of these outcomes, there was no significant difference found among women who had C-sections versus women who had vaginal births.

The only two complications that differed across groups were urinary incontinence and pelvic organ prolapse. Both are actually more common for women who have had a vaginal delivery. The findings makes sense biologically. There are reasons why the loosening associated with a vaginal delivery would lead to these risks. Both of these conditions are treatable, to some extent. While this doesn’t represent a strong reason to favor C-sections, the study certainly suggests there isn’t any reason to malign Cesareans over recovery concerns.

Does a C-section Affect the Baby?

At first glance, it is unclear why the method a child was delivered would matter, especially in the long-term. And for many outcomes, it doesn’t. The breech delivery randomized trial shows convincingly, for example, that infant mortality and developmental outcomes at age two are unrelated to method of delivery.

However, there’s speculation that how a baby is delivered could have an impact on whether or not they develop diseases like asthma and childhood obesity. Why might this be? One possible reason is the microbiome, your personal collection of microbes and bacteria that are thought to be linked to all kinds of health outcomes. Researchers have shown that when an infant passes through the vaginal canal they acquire their mother’s bacteria, which then colonizes the infant’s own microbiome. Delivery by C-section clearly interferes with this process.

Researchers have speculated — and I stress, speculated — that this initial microbiome seeding is important for avoiding autoimmune diseases like asthma and obesity. There’s no direct evidence of this. What we do have — and what we can see in the 2018 meta-analysis — is the rate of asthma and obesity among kids delivered by C-section or vaginally. And that evidence does point to a higher rate of asthma and obesity among children born by C-section. The absolute increases in both cases are fairly small, although the effects are significant.

I find this evidence interesting but problematic. The choice to have a C-section is associated with many other features of the mother including weight, medical conditions, and, at least in the U.S., characteristics like income and education. These factors are also associated with asthma and obesity, and it is a significant, probably not surmountable, challenge to fully control for them.

All of this is to say that while we should look forward to more evidence on how birth might impact a child’s microbiome, women whose children are born by C-section should not feel that they have somehow failed their children and doomed them to a life of illness. If you are very worried, some people have considered “vaginal seeding” (rubbing vaginal secretions on the infant) as an approach to reconstituting the microbiome. I caution that this is not recommended by everyone and the safety is uncertain. Supplementation with a probiotic, combined with breastfeeding, may have similar impacts.

Can a C-section Affect Future Pregnancies?

How a woman’s delivery impacts her future pregnancies is where the risks of C-section become more significant.

Most notably, if you have a C-section for one birth — or, especially, for more than one — the risks of complications with the placenta in later pregnancies are dramatically increased. This includes placenta previa, where the placenta covers the vagina; placenta accreta, where the placenta invades the uterine wall; and placenta abruption, where the placenta detaches from the uterine wall during pregnancy. The latter two complications are rare, but extremely serious for both baby and mom, and the risks are significantly elevated if a woman has had an earlier C-section. Other future pregnancy complications also appear more common — ectopic pregnancy, miscarriage, stillbirth, pre-birth bleeding.

I should note that there are also concerns that these differences in birth outcomes are actually due to differences in who is having a C-section in the first place. However, the link between a C-section delivery and these complications is made more convincing by the fact that there is a clear biological reason for them. The necessary injury to the uterus during a C-section contributes to a higher risk for these results.

It is important to emphasize that all of these complications are rare, so the absolute increase in risk is very small. Many women have multiple C-sections, and pregnancies afterwards, with no complications at all. Still, it’s important to acknowledge where there do seem to be risks.

Decision Time

There is no universally agreed upon level of C-sections that is optimal; the World Health Organization (WHO) historically suggested they were necessary in 10 to 15 percent of births, but have since taken out this specific number, concluding it is impossible to know what the right number of C-sections is. What is crystal clear is that there are many situations in which a C-section is absolutely necessary and recommended. If your baby is breech, evidence shows a C-section is the right choice. If labor fails to progress, or the baby is stuck, or the mother or child is not tolerating labor well, access to emergency C-sections is crucial and lifesaving.

And to the women who worry that somehow their infant is missing out on some crucial vaginal secretions or some important life experience, the data says you should relax.

As to the question of whether you should plan a C-section, my read of the evidence is a qualified no. In particular, if you are planning to have more children, the data makes clear there are some important downsides to this choice. They are not insurmountable, but they are real risks.

C-sections have come a long way since Jacob Nufer’s procedure in the 1500s. I started this article, like I started my pregnancy, with the assumption that C-sections are a “second best” delivery option. And in a sense I still think that, for most women, this is true. However, we cannot lose sight of the tremendous value of the C-section to many women. And more than that, we cannot lose sight of the value of a healthy mom and baby, no matter the method of delivery.