More on cesareans and obesity

Cesareans? Really?

Does cesarean birth put a baby at increased risk for obesity in the future? Seems a little far-fetched at first glance, but Dr. Susanna Huh and her Harvard colleagues just published a study that makes the link a bit more “near-fetched.” (The study itself is available here.)

Huh’s team found that children born by cesarean section were twice as likely to be obese at 3 years of age than were those born vaginally. This relationship held up even when factors like the mother’s weight, ethnicity, age and how many babies she’d already had  were taken into account. Interestingly, it didn’t make a difference whether the cesarean was performed before or after labor started.

The study wasn’t designed to look at the reasons for the increased risk in obesity, but the Harvard team suggested several possibilities:

The first is the alteration of the gut microbiota–the sum total of all the bacteria found in the human bowel–caused by a cesarean birth. (More detail on that here and here.) This alteration can lead to low-level inflammation in the bowel which is associated with obesity.

The second possibility is that cesarean birth is just a stand-in for something else that’s happening at the same time. In this case, Huh and colleagues wonder about all the antibiotics given to women who are having cesareans. Antibiotics are known to alter the gut microbiota, but research results are mixed as to whether this is a lasting effect.

Finally, it’s possible (though unlikely) that all of this has nothing to do with the gut microbiota. There are hormones and other factors related to inflammation that surge in a mother’s bloodstream (and her baby’s) during labor, and these, obviously, are missing if a mother undergoes a cesarean before she starts labor. The lack of maternal stress response during labor could adversely impact the development of the newborn immune system, leading to the inflammation associated with obesity.

My best guess: it’s a big moosh of all of the above, plus other factors no one has even dreamed of yet. In the meantime, the issue of increased obesity risk is one more thing physicians and pregnant women should consider before deciding on how a baby is to be born.

It’s a complicated matter, this business of hatching healthy humans…


Filed under Cesareans, Obesity

6 responses to “More on cesareans and obesity

  1. I agree that it’s probably a big “moosh” but I’m no scientist or doctor and I’m not patient enough to read the study. I was wondering if more obese women end up needing cesareans?


    • Hi Eileen,
      Yes, obese women are more likely to have a cesarean than are women of normal weight. Part of that is due to the fact that they have a higher risk of the kind of chronic diseases–diabetes and hypertension, mainly–that can lead to a cesarean for any woman. But obese women have a harder time with “failure to progress”, too–that’s when labor stalls after it starts, which is a set-up for a cesarean. No one is quite sure why that is–it’s possible that being overweight may have some impact on the hormones that guide labor. But the Harvard study showed that a mother’s weight didn’t have any bearing on the chances of her baby later becoming obese, which was unexpected.
      Thanks for writing!


  2. Also think included in that moosh would be the interference with breastfeeding that a cesarean causes. Wondering if there are any studies following the breastfeeding success rates of cesarean born mother-baby duos?


  3. If there’s reason to think that subjecting the baby to the flora and fauna of the birth canal is a good idea… why not do it after the C section? It wouldn’t be that hard to take a swipe and feed it to the baby. Would that be ineffective? Is it too odd to do in polite society?


  4. Hi Ania,
    I’ve searched but I can’t find any studies about this. I’ll keep looking. It seems like it would make sense to try this, and certainly be harmless, but I can’t find any evidence of efficacy. Thoughts off the top of my head: I don’t think you could match the dose of bacteria a child would get during birth that way. Also, the hospital bugs would get in there pretty quickly once the cesarean baby is delivered–they wind up to a lesser extent in babies born vaginally in hospital, according to one study. But that’s not to dismiss it – I hope I find something on this in the literature. Let me know if you come across any.
    Take care,


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