Epigenetics and delivery

In earlier posts I discussed how studies on rats have revealed that early life experiences modify the epigenome, which has long term consequences for stress responsiveness, reproductive behaviors, and obesity rates. It’s often difficult to do epigenetic studies on humans due to ethical concerns, but some pretty clever work has been done lately revealing that the results from the rat studies may be broadly applicable.

ChildBirthI found this article recently that describes a study comparing the methylation patterns of children delivered naturally to children delivered by C-section. They found that the section of the epigenome which codes for white blood cells is more heavily methylated in children born by C-section, perhaps because this procedure is more stressful for the child than natural birth.

We already know that children delivered by C-section are at a greater risk for diabetes, allergies and leukemia and the researchers who ran this study postulate that these greater risks may be the result of changes in methylation patterns during delivery.

It’s unclear whether the methylation patterns is caused by the procedure per se or by the mother’s stress over whatever complications are resulting in the need for a C-section in the first place. Further studies will be needed, but (as I mentioned in a previous post) some studies have already concluded that the fetus’ epigenome is altered when mothers are stressed out or depressed during gestation.

If researchers can convincingly make the claim that C-sections change methylation patterns (and therefore patterns of gene expression) in babies and that these changes in gene expression result in a greater risk for particular diseases, then perhaps we’ll see the trends in C-section rates reverse. At the moment, the percentage of deliveries that are done by C-section is steadily increasing worldwide.

I was under the impression that most C-sections were done when there were complications that put the mother and/or the baby at risk, but it looks like there are plenty of less serious reasons for why women get this procedure done. Some mothers elect to have C-sections so that they can “maintain vaginal tone” (i.e., they don’t want to become “loose”) or because they don’t want to experience the pain associated with childbirth.  Doctors are also inclined to perform C-sections at the slightest hint of a complication because this could save them from dealing with expensive malpractice suits.

I’d be interested in seeing if differences in the prevalence of particular diseases between countries could be correlated with country specific C-section rates. For example, Brazil has the highest rate of C-section delivery and I would be interested in finding out if they also have high rates of diabetes, allergies and leukemia as well.

Hopefully clever research will teach us more about the link between C-section, the epigenome and the risk of contracting particular diseases. If a clear link is found then we may see a big change in the way the public perceives non-emergency C-sections.


11 thoughts on “Epigenetics and delivery

  1. If the different methylation patterns are due to the mothers’ stress over complications, then you’d expect there would be less of a difference in the case of elective C-section.
    I guess I’ll have to wait for further research to decide the issue. It’s not like there’s a pile of data online for me to rummage through so I can find out myself. That would be nice, though.

  2. If the mother’s stress can alter the methylation patterns, then what effect do drugs used before and during delivery – epidural, etc. have on the child? Raises a lot of questions about how well we understand what occurs as a result of birthing procedures, and a whole lot else. How early is an “early life experience”? What effect might various pediatric practices have. Interesting stuff.

    • There was quite a debate about this here in Sweden recently. As far as I could understand, it was mostly the stress levels of the child that were the main course of concern. Natural birth means that the stress levels of the child go up gradually while in a C-section it all happens at once.

      Could be that the physical effect of contractions has something to do with it. If I remember correctly, it releases endorphins too. Even afterwards in life the act of squeezing or hugging someone releases quite a bit of them feel good endorphins!

    • My mother had a C-section due to being given too much in the way of painkiller drugs, causing her contractions to stop. So that would be a rather different “stress” scenario….

  3. I’d be interested to see if C-sections increase right before New Years, so parents can get the tax break of an additional dependent for that year.

  4. I feel the trend of C-Sections is part of a growing “ultra-sterile” idealism that is dangerous to us as a species. From pet allergies to resistant strains of bacteria, too clean too often results in serious and irreversible damage.

  5. A friend of mine wrote up an article on this study, apparently despite achieving statistical significance, the study’s sample size was literally only 37 babies. The power of this study is so astronomically low that there’s really no way to tell for sure whether or not it’s actually true or not. That said, it does indicate a very interesting point for further studies.

  6. Notes on the rising rate of C-sections:
    While C-sections are more convenient for mothers and physicians (they can be scheduled and are much less variable in terms of how long they take), there is also other factors that are making C-sections more common. (1) In the past, obstetrician/gynecologist were skilled at assisting vaginal deliveries with forceps. Unfortunately, the skill of forcep use is hard to teach (it’s hard to see what the teacher is doing) and it just takes practice to learn how to use them. There is more operator-variability. In contrast, a C-section is a much more standardized procedure and much easier to teach. In some cases forceps delivery would be preferable to a C-section, but fewer and fewer people know how to handle forceps, so they reach for a scalpel instead. (2) Also, once a woman’s uterus has been incised, she is at risk of her uterus rupturing (a truly life threatening emergency for mother and child) if she attempts to use that muscle to push any subsequent babies through the vaginal canal. So C-sections beget subsequent C-sections. (3) In terms of sterility, the only indication for a C-section as opposed to vaginal birth is when the mother has conditions such as HIV or active Herpes lesions. Delivering by a C-section has been demonstrated to significantly reduce the child’s likelihood of contracting the illness, which can be especially severe in the setting of a newborn’s immature immune system. (4) The health care system does much more monitoring of the baby’s heart rate nowadays, and so we catch many more “non-reassuring” patterns that do indeed drive people to get C-sections more often. It’s been shown that not all of these babies are necessarily urgently in need of delivery (and therefore C-sectioning) — but, in addition to wanting to avoid lawsuits, no doctor wants to tell a patient that her baby died when it might have lived if they did a C-section instead of trying a little longer for a vaginal delivery. I’m sure there are other things I could think of, but not off the top of my head…

  7. “Some mothers elect to have C-sections so that they can “maintain vaginal tone” (i.e., they don’t want to become “loose”).”
    I’ve never thought of it that way. I was born by C-section because I was a breach baby with some kind of ridiculous umbilical cord wrapping. My mother hated it, as when they cut her open all those muscles settled back in different places and she said her body was never the same (plus, she hates scars).

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