Category Archives: Cesareans

Mode of delivery and childhood illness: A randomized trial in 2004.

03c62f38ce31d41b01e1b5a4031bf11aOne of the biggest difficulties in proving a causal link between cesarean birth and chronic health problems in childhood is the type of research studies that can practically and ethically be done during pregnancy.

The gold standard in medical research is the randomized controlled trial (RCT). In an RCT researchers randomly place subjects into either “treatment” or “control” groups, then expose the treatment group to something—a new vaccine for Infection X, for example—and then compare outcomes in the two groups later on. (In this example, how many kids in the treatment [vaccinated] group came down with Infection X versus how many in the unvaccinated control group?) If there’s a significant difference in outcomes between the two groups, you’ve got a strong argument that the treatment made the difference.

How a randomized controlled trial works. (Credit: SUNY Downstate Medical Center)

How a randomized controlled trial works.**

As you can imagine, randomly assigning pregnant women to cesarean (treatment) or vaginal birth (control) groups is nigh onto impossible—ergo, you can’t do an RCT. This means that virtually all research studies on the issue of cesareans and chronic childhood have been observational in nature—looking backward in time at databases, for example, or trying to fish significant trends out of hospital registries, birth cohorts and the like. The best an observational study can tell you is that A and B are associated with one another, but that’s it—you can’t prove that A actually causes B. An observational study can’t prove that cesareans are a cause of asthma; it can only say that cesareans are associated with an increased risk of childhood asthma.*

So mode-of-delivery RCTs are out of the question…or are they? Actually, in 2004, a Canadian research team did one.

Well done, Northern Neighbors!

Well done, Northern Neighbors!

The multi-center, multi-nation Term Breech Trial wasn’t about whether cesareans might increase the risk of childhood asthma, diabetes and such. It was about trying to figure out whether elective cesarean section or vaginal birth was the safest way to deliver a breech baby at term. Since the existing research was somewhat murky at the time, it was considered ethical (with informed consent) to randomize women to have either a planned cesarean or attempt a vaginal birth.

The particulars of the breech birth debate are best left for another post, but tucked away in the study’s results section was this little nugget:

“…more parents in the planned cesarean birth group than the planned vaginal birth group reported that their children had had medical problems in the past several months…relative risk, 1.41; 95% CI, 1.05-1.89; P=0.2.”

Plain English version (mine): The toddlers who had been in the planned cesarean group were about 40% more likely to have been sick in the previous few months than those in the planned vaginal birth group. The types of medical problems—typical 2 year-old stuff like colds, ear infections and stomach flu—were no different between the groups. The only difference was in the numbers of children who’d gotten sick.

As is the case with all medical research, you can find things in the study to complain about: relatively small numbers, for example, the use of parental questionnaires and the fact that some mothers in planned vaginal birth group ended up having cesareans (and vice-versa), etc.

But here’s my bottom line:

In a randomized trial of pretty well-matched subjects, those babies whose mothers were in the planned cesarean group tended to get sick more often than those in the planned vaginal birth group.

This doesn’t address the issue of chronic illnesses like asthma, type 1 diabetes and the like, but it does support the theory that cesarean birth can mess with a baby’s developing immune system.

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*Here’s an exaggerated example of the trouble with mistaking association for causation: Virtually all adults who die suddenly of heart attacks drank water in the 24 hours before they died. So, drinking water is associated (time-wise) with heart attacks. But you would be wayyyy wrong to say that, based on that association, a glass of water can cause a heart attack.

**Credit: SUNY Downstate Medical Center

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Filed under Asthma, Canada, Cesareans, Immune system, Maternal-child health, Newborns, Vaginal birth

Cesareans and chronic childhood disease: Time for a public discussion

From the Ishinhō, Japanese medical text, 1860

From the Ishinhō, Japanese medical text, 1860

In an analysis published in the most recent edition of The BMJ, Drs. Jan Blustein and Jianming Liu examine the evidence that cesarean delivery is associated with an increased risk of chronic childhood diseases like asthma, type 1 diabetes, and obesity. Their conclusion: the bulk of the evidence suggests that the association is real.

The time has come, Blustein and Liu write, for maternity care providers to include the risk of chronic childhood disease in their discussions with women considering a “non-essential” cesarean, such as when the choice is between a VBAC or repeat cesarean, or in the case of a woman choosing a medically unneccessary cesarean in lieu of vaginal birth—the so-called “maternal request” cesarean.

This topic has intrigued me for some time now. As part of my recently completed MPH program at the University of Minnesota, I wrote a paper titled, “Do Cesarean Sections Increase the Risk of Child Asthma? A Systematic Literature Review.”

In writing the paper I read and analyzed every research study on the subject since 2001. Roughly two-thirds of those studies detected a small-to-moderate association between cesarean birth and childhood asthma. (In fact, 90% of the studies detected an association between the two, but not all were statistically significant.) Most of the studies that didn’t find the association were seriously flawed—too few subjects, for example, or ignoring possible confounders, like prematurity or a history of maternal asthma. Three meta-analyses (two in 2008, one in 2014) all reached similar conclusions: cesarean section is associated with about a 20% increase in the risk of child asthma.

My paper was limited to asthma, but as described in the BMJ analysis there’s evidence that cesareans increase the risk of other chronic childhood illnesses, too–type 1 diabetes and obesity. A 2015 study by Sevelsted et. al. analyzed a cohort of two million Danish children and found small-to-moderately increased risks of juvenile rheumatoid arthitis, connective tissue disorders, inflammatory bowel diseases, immune deficiencies, and even leukemia.

Given that body of evidence, you’d think that organizations like ACOG (the American Congress of Obstetricians and Gynecologists) and the U.K.’s National Institute for Health and Care Excellence would be pushing their members to share this information with their pregnant patients. But they’re not. According to Blustein and Liu,

“…knowledge about chronic disease risks could affect decision making in non-essential caesarean. The American College of Obstetrics and Gynecology and the UK’s National Institute for Health and Care Excellence recently issued consensus statements on caesarean delivery at maternal request. Based on evidence about maternal and perinatal outcomes, both groups concluded that a pregnant woman requesting caesarean should have that choice, if she still desires it after discussion of the risks and benefits of the procedure. Importantly, neither group acknowledged the long term risk of chronic disease. [Emphasis mine.]

Critics can (and do) point to the uneven quality and designs of the studies that support such links—it’s association versus causation all over again—but that’s not entirely fair. To prove beyond doubt that cesarean birth increases the risk of child asthma, you’d have to do trials where women are randomly assigned to cesarean or vaginal birth…which, as you can imagine, is a practical and ethical non-starter. That leaves us with observational studies, which can only point out that two things seem to be related, not that they definitely are.

Ah, but there has been a randomized study of the long-term effects of cesareans versus vaginal birth in term, breech deliveries, and at least one research team has made the case that randomized trials of mode of delivery aren’t really unethical. More on those topics soon.

Finally, just to re-re-reiterate: I’m not anti-cesarean. My wife and son are alive and well today thanks to a medically necessary cesarean. But the cesarean rate today is 6 times higher than it was when I was a junior in high school (1970, if you must know…). As Blustein and Liu point out in their analysis:

“We live in a world where caesarean rates cannot be explained by compelling medical indications.”

Perhaps increased awareness of the potentially negative impact of cesareans on child health will help reverse that decades-long trend.

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Filed under Asthma, Cesareans, Diabetes, Obesity, VBAC

Is it the cesarean, or the absence of labor?

Stem cells, pondering the future

Stem cells, pondering the future

I’ve written a fair amount about the association between cesarean birth and the increased risk of immune-related diseases like asthma, diabetes, celiac disease, and even obesity. Most of the research out there has focused on the newborn gut microbiota—the collection of bacteria that colonize a baby’s intestines at birth and play a key role in the development of the immune system. These bacteria are primarily acquired from the mother’s birth canal and rectum during a vaginal birth, but for cesarean-born babies those “pioneer” bacteria are often derived from the hospital environment. Such “wrong” bacteria in the bowel early on can lead to inflammation and, the theories go, to immune-related diseases later in life.

But is the cesarean per se at the root of all this? Or might the absence of labor (or an incomplete labor) have something to do with it? Childbirth is, after all, a fabulously complicated dance of maternal and fetal hormones, anti-oxidants, and other chemicals that are known to influence the immune system. What happens to the newborn’s immune system development when that dance is cut short, or never starts in the first place?

A study from Sweden’s Karolinska Institutet published in the current issue of the American Journal of Obstetrics and Gynecology has me wondering about the “absent-labor” scenario again. The study’s authors compared cord blood samples from babies born by elective cesarean section (ECS) with those who were vaginally born (VB). They looked specifically at hematopoietic stem cells—the precursor cells that go on to become, among other things, the white blood cells that play a critical role in the human immune system.

Here’s what they found: the DNA in stem cells from ECS babies was significantly different from that of the VB babies, particularly in an area devoted to production of antibodies. The study’s genetic analysis is way above my pay grade, but boiled down to the essentials, the differences are all about epigenetics, which is defined as:

 “…the study of changes in gene function that are mitotically and/or meiotically heritable and that do not entail a change in DNA sequence.”

Ouch!

Plain English version (mine): Epigenetics is the study of how genes are turned on and off, typically by the addition of methyl groups (ouch, again!) to genes. The timing of all this light-switch-like activity, and the potential for permanent change, has big-time implications for health throughout life.

The Swedish researchers found that stem cell DNA methylation (the addition of methyl groups to genes) increased steadily with the duration of labor. So one could conclude, couldn’t one, that normal labor plays an important role in preparing future white blood cells for their task, and, ergo, the absence of labor is why everyone’s so chubby these days? Sure, one could conclude that…but one would be jumping the gun, big time.

Hold that smokin' gun, pardner!

Hold that smokin’ gun, pardner!

Why? Because this was a small, observational study—the kind of study designed to make readers sit up and take notice (Hmm…that’s interesting!”) but that requires much more research before any guns start smoking. The small numbers of subjects in this study makes it easier for error to creep in, for example, and there were significant differences between the mothers as well—the ECS group was significantly older than the VB group, and their babies were born an average of a week and a half earlier, factors which might cause their own epigenetic effects.

It’s going to take much larger studies to see if these findings are in fact true, and if so to tease out how significant such cesarean-related epigenetic changes may be in the grand scheme of childhood immune system diseases. A lot of vaginally born kids end up asthma, after all. Including me.

But still, how fascinating! I’m looking forward to reading more about this.

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Photos courtesy Joseph Elsbernd, Jim Sher

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Filed under Asthma, Cesareans, Gut microbiota, Natural childbirth, Obesity

Australia

Neighbors, north of Sydney

Neighbors, north of Sydney

Just back from three weeks Down Under, where I was invited to address the Rural Health West Annual Conference in Perth. The theme this year was “Children of All Ages: Health Across the Continuum in Rural Communities.” It was a wonderful experience, and I’m grateful to Belinda Bailey and the organizing committee for their warmth and hospitality.

I gave the keynote address (“Unintended consequences: How mode of delivery impacts long-term child health”) on the mounting evidence that cesarean birth increases the risk of a number of chronic illnesses later in childhood. (For previous posts on the subject, see here and here.) Lots of discussion followed–the cesarean saga in Australia has paralleled that in the U.S., and in sparsely populated Western Australia, where hours-long air transport to a tertiary care hospital is common, decisions about when to intervene in a woman’s labor are particularly challenging. As here in the U.S., a popular movement is pushing back at unnecessary cesareans, or “caesars” as they’re known in Australia.

Later that day I spoke on the history of neonatal resuscitation, a talk loaded with odd historical tidbits, as is my habit… (Did you know that newborn babies in ancient Greece were salted and coated in honey (scroll link to page 82) to protect them from infection? Or that midwives were performing

Perth, From King's Park

Perth, from King’s Park

mouth-to-mouth resuscitation on sick newborns as early as 3,000 years ago? Or that in Germany, the accepted means of reviving a sick newborn until well into the 20th century was to simply swing them up and down?) That talk always gives an audience an appreciation for modern resuscitation equipment.

Perth is a beautiful city, more or less the San Diego of Australia. The weather was gorgeous, and my wife Elisabeth and I did quite a bit of touring around. Became fairly familiar with a number of marsupials, including a few we’d never even heard of. (Numbats, anyone? Quokkas?) We spent a week in and around Sydney, too (over on the east coast, for those of you not up-to-date on your geography)–another fascinating city. We finished up with four days in a cottage in a national park, which is where my kangaroos-in-the-field photo at the top was taken.

Talking cesareans with new friends

Talking “caesars” with new friends.

Oh, and I actually drove over 400 miles on the “wrong” side of the road without so much as a scratch on our rental car, let alone the fiery chain-reaction pile-up (my fault, of course) that I’d been expecting…

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The Brazilian preference?

4753658072_3816f74c0d_nWhat happens when a woman emigrates to a foreign country and then gives birth? Is her birth experience more likely to conform to the country she comes from, or the one she moves to?

For example, is an immigrant woman more likely to have a cesarean birth than a native-born woman, or less? How big a role do the cultural norms and expectations she brings with her from her home country play in determining mode of delivery?

Studies of immigrant birth experiences have been mixed to date. Immigrants do tend to have higher cesarean rates than natives, but interpretations of such findings are often complicated by things like language barriers and the difficulties new arrivals may have in accessing timely maternity care. Teasing out the effects of culture can be tricky.

A Portuguese article just published in the journal PLOS ONE helps to clarify this issue. The study compares cesarean rates between native-born and immigrant Brazilian women in northern Portugal. Two major potential confounders are quickly dealt with: the two groups of women both spoke Portuguese, which eliminates language barrier as a source of cesarean-inducing miscommunication, and all the women were drawn from five public hospitals, so that the care they received was more or less uniform.

The authors found that Brazilian immigrant women had a 50% higher cesarean rate than did native-born Portuguese women (48.4% vs. 32.1%), a difference that persisted even after controlling for such things as demographic, medical and obstetric risk factors. In fact, the cesarean rate for Brazilian immigrants was nearly identical to the overall cesarean rate in Brazil itself.

What explains the native-immigrant difference? The authors speculate it has much to do with attitudes about childbirth that the women brought with them from Brazil:

“This extremely high prevalence [of cesarean birth] seems to be a cultural consequence of attitudes towards labor and the perception of obstetric care among Brazilian women. The majority of Brazilian women perceive cesarean as the most adequate mode of delivery and as a symbol of high social status.”

In other words, culture strongly influences mode of delivery, even far from home. A woman raised to see cesarean birth as a desirable norm is much more likely to end up having one.

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Birth centers: Safe, economical, and great places for low-risk births

2852282606_22551640c8An American woman with a low-risk pregnancy who chooses a midwifery-led birth center for her maternity care is four times less likely to have a cesarean than if she chooses a hospital birth, according to a review published today in the Journal of Midwifery & Women’s Health.

The review highlights the findings of the National Birth Center Study II (NBCSII), which followed 15,574 women who planned and were eligible for birth center births at onset of labor.

Among the NBCSII’s findings:

  • 84% of women who planned and were eligible for a birth center birth at onset of labor were successful in having one.
  • Only 6% of women intending a birth center birth ultimately required a cesarean section, compared with nearly 24% of comparably low-risk women receiving care in hospitals.
  • Emergency transfers from birth center to hospital were uncommon.
  • Fetal and newborn deaths were rare, and comparable to those in low-risk births in hospital settings.
  • There were no maternal deaths.
  • Birth center care is economical and in keeping with the fiscal goals of the Patient Protection and Affordable Care Act (aka “Obamacare”).

Some nuts and bolts of the NBCSII, FAQ-style:

What, exactly, is a “birth center”?

  • The American Association of Birth Centers defines a birth center as “a homelike facility existing within the health care system with a program of care designed in the wellness model of pregnancy and birth.” The key here is “within the health care system”—the integration between birth center and hospital is critical to the success of any birth center. When emergencies arise, a smooth transfer is vital to keeping mother and baby safe.

Who runs these birth centers?

  • The birth centers in the study were all midwifery-led. 80% were staffed by certified nurse midwives (CNMs), 14% by certified professional midwives (CPMs) or licensed midwives (LMs), and the remaining 6% by teams of CNMs,  CPMs, and LMs. (The different types of midwives in the U.S. can be a bit confusing for the layperson—the American College of Nurse-Midwives provides a handy comparison chart.)

What is a “low-risk” pregnancy? Who qualifies for a birth center birth?

  • Here are the AABC’s eligibility requirements for birth center birth: a single fetus in head-down position, with no medical or obstetrical risk factors that might interfere with normal vaginal birth or require interventions like continuous fetal monitoring or labor induction.
  • By those standards, approximately 85% of pregnancies are “low-risk.”

Why did 16% of the women who planned a birth center birth end up giving birth in hospitals anyway?

  • Of that 16%, about one-fourth were transferred to hospitals before being admitted to the birth center, due to medical issues. Of the rest, the majority were for non-emergency problems, such as prolonged labor. Only 0.9% of the birth center women required an emergency transfer during labor.

Is birth center birth really as safe as hospital birth?

  • Yes, according to the NBCSII’s findings. The rates of fetal death (4.7/10,000 women admitted to a birth center in labor) and neonatal death (4/10,000) in the study were comparable to those in other studies in the U.S. and elsewhere, including those of low-risk birth in hospitals. There were no maternal deaths.

Does birth center care really save money?

  • Yes. In this study alone, cost savings–mainly from fewer medical interventions (including cesareans)–were estimated at more than $30 million, and these 15,574 pregnancies represent less than 1% of all U.S. births. Given that expenses for hospital birth in 2008 exceeded $97 billion nationwide, the opportunity for savings in these health-care-dollar-scarce times is enormous.

A few quibbles:

  • The women in the study were mainly white (77.4%), well-educated (71.8% had at least some college education, and 51.8% were college graduates), and married (80.1%). They were also relatively slender (only 5.7% were overweight or obese, compared with more than 50% of all pregnant American women), mentally healthy (3.3% were being treated for depression or other psychiatric disease), and largely free of substance use (1.5% smokers, 0.5% users of other substances). Though the study’s findings on safety and cost-savings compare favorably with other studies of low-risk pregnancy outcomes, it isn’t clear that these findings can be extrapolated to the U.S. population as a whole.
  • Death rates are crude tools for measuring safety, particularly in low-risk pregnancies. I’d like to know more about morbidity–were the birth center babies more, less, or just as likely as hospital-born babies to suffer birth trauma, for example? I suspect they were less likely to have such complications, given the tendency of birth center staff to perform fewer interventions, but I can’t be certain from this study. Hopefully that will be addressed in a future review.
  • What about breastfeeding? Were the birth center mothers more likely to breast feed than those who gave birth in hospitals? Again, I suspect so, and hope that information on breastfeeding will appear in future reviews of NBCSII data.
  • The 79 birth centers that participated in the study represent only 32% of American birth centers. All 79 are AABC members and as such support the AABC’s Standards for Birth Centers. Other, non-member birth centers may or may not adhere to such standards, and their safety records may or may not be as good as those in this study. With new birth centers appearing at a remarkable pace (up 27% since 2010), ensuring high quality care in all birth center settings may be challenging.

Conclusion:

Withe the publication of this review, the well-entrenched belief that hospitals are the safest place to have a baby takes yet another beating. It’s increasingly clear that most women with low-risk pregnancies can safely give birth at midwifery-led birth centers. A personal/professional note: I’ve taken care of a number of families who’ve had their babies at the Women’s Health and Birth Center here in Santa Rosa, California, run by Rosanne Gephart, CNM. (Rosannne and I go way back). They speak glowingly of their experience at the Birth Center.

One caveat, though. Not all birth centers are alike, and it behooves expectant parents to check out things like staff credentials and birth center accreditation, and to ask pointed questions about how the center handles emergencies and hospital transfers, and how often these occur. Membership in the American Association of Birth Centers is a plus, too. Whether choosing an auto repair shop, a law firm, a pediatrician, or a birth center, it definitely pays to do your homework.

Photo credit: JER_0079

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Things Kids Say: The ABC’s of surgical birth

Thinking, thinking…

“So that makes me the B-section.”

Will, age 6, explaining that since his newborn brother was born by C-section, his big sister must have been an A-section, which logically left him in the alphabetical middle of the birth order.

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Photo by estoril

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