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ask dr leigh: c-sections vs DNA

By | July 4, 2009

Dear Dr. Leigh,
You may have already seen this but… Apparently, Swedish researchers found that c-sections trigger DNA changes that could be responsible for later-in-life diseases – ie allergies, diabetes, leukemia. What do YOU think?

dear friends,
here are some of these articles currently making a splash:
C-Section Stress Could Alter Baby’s Immune Cells: “C-section birth increases the risk for asthma, allergy, diabetes, and leukemia, and the reason might be altered birth conditions that change immune cells.”
C-section Births Cause Genetic Changes That May Increase Odds For Developing Diseases In Later Life: “Babies born by Caesarean section experience changes to the DNA pool in their white blood cells, which could be connected to altered stress levels during this method of delivery, according to the July issue of Acta Paediatrica.”
Epigenetic modulation at birth: Altered DNA-methylation in white blood cells after Caesarean section: “As the diseases that tend to be more common in people delivered by C-section are connected with the immune system, we decided to focus our research on early DNA changes to the white blood cells.”

a LOT of babies are born by cesarean (which is why these news stories will make a big splash)! here are some local statistics on cesareans:

according to the oregon vital-statistics bureau, in lane county, oregon, in 2008, the local catholic hospital system (i won’t name any names) had about a 34% cesarean rate (995 sections in 2929 total births), and the local non-catholic hospital had a 30% rate (246 sections in 823 total births).
this year, the initial figures for january through march (2009) report a 32.8% rate for the catholic hospital and a 34% rate for the non-catholic hospital.
(the figures do go up and down month by month.)
(p.s. i LOVE the oregon vital-statistics website!)

back to the news. i give it both a thumbs up and thumbs down – thumbs up, for drawing attention to the unintended effects of birth stressors; thumbs down, for catastrophizing. let me explain.

they’re basically saying the immune system (“white blood cells”) starts reacting right away, to whatever it’s exposed to after birth. and that makes sense, doesn’t it? babies develop in a sterile environment (unless some extremely rare infection occurs during pregnancy), and their little bodies are sterile at first, as you know, with no bacteria in their guts or their airways or anywhere else.

babies who are born by cesarean are more likely to be under greater physical stress in the first place – they pretty much get unceremoniously yanked out, then suctioned out, cord clamped immediately, and so on. they usually go to straight to the nursery, and are much more likely get a lot of tubes placed (ventilated airway, nose-to-stomach feeding tube, bladder/urethra catheters, indwelling line in vein), for getting laboratory samples out and nutrients or medicines in. they’re also more likely to get multiple x-rays, which have effects on the immune system and are never taken lightly.

plus – in the events often leading up to a cesarean – they would most likely have had an artificial rupture of membranes (removing the baby’s sterile saltwater barrier), ever-more-frequent vaginal exams (feeling baby’s head as well as the cervix) by gloved fingers, a pressure sensor cable indwelling in the uterus, and a heart monitor screwed into the skin of the baby’s head. so they’ve got a lot of unexpected exposures to react to, there, even without a cesarean birth. it would not be surprising that their little immune systems would wake up and smell the coffee.

some of these immunological exposures occur as part of a careful risk-benefit analysis (better to have a ventilator tube in your throat, than to not breathe at all). others occur as a “might as well, why not” kind of analysis (we could speed up this labor if we break the waters, might as well, why not).

compare these immunological exposures to those involved in a minimally-invasive birth at home*, where the regular household germs attract no more immunological attention than they already did when mom was exposed to them daily.

for example, mom cleaned out the closet and got a bit of dust and mold in her face, and sneezed a few times; her immune system reacted to it; some of the resulting antibodies went around in the fetus’s bloodstream; now the baby’s immune system is not going to be astonished when it encounters the same traces of dust and mold on the baby-blanket brought out of that same closet. mom will probably have her cervix checked a few times by gloved fingers while she labors, but for the most part the invasions will be very few. and as you know, one of the most excellent things about breastfeeding is the wealth of immunological factors (in colostrum and milk) that coat the baby’s entire – sterile – GI tract after birth. (breastfeeding is often complicated or postponed altogether, in the hospital +/- cesarean setting.)

ideally, then, from an immunological perspective, the baby’s and mom’s “mutual immune system” is not suddenly confronted, during or after birth, by an undue amount of stressful novelty.

*(for more info on home birth, see among others the Southern Oregon Homebirth Study – cesarean rate = 5.24% of moms who planned a home birth [8.8% were transported to the hospital for various reasons altogether, and most had a cesarean after arrival]. note: i do not practice midwifery; i just know a lot about it!)

so, anyway, yes, in my opinion, climbing the birth-intervention ladder probably means climbing the immunological-reactivity ladder too.

however, humans and other big complex creatures are pretty darned resilient! as you know, giraffe babies are born from a great height, land in a cloud of dust, and basically jump up and get busy within that first hour. kittens and puppies have been born in dumpsters, in nests of fiberglass, in a postal carrier’s bag, in a combine harvester, and grew up happy and healthy. and, of course, human babies are born into every walk of life (note the infant mortality rates of serbia and croatia – only a bit worse than the u.s., which in turn is just a bit worse than cuba, and nowhere near approaching the excellent statistics of slovenia, the czech republic, macau, or singapore*) – and the vast, vast, vast majority do a-ok.

*fun facts to know and tell:
“average wealth” = GDP = per-capita “purchasing power,” 2008 figures.
fertility rate and infant mortality rate = 2009 figures.

croatia, where the average person’s wealth is $16,000 per year,
is 47th (of 224) in infant mortality (6.37 deaths under 1 year old, per 1000 live births).
croatian ladies of childbearing age have an average of 1.2 babies during their lifetime.
this means 100 croatian women of childbearing age would have 120 babies, altogether.

cuba, where the average wealth is just $9,500 per year,
is 44th (5.82 deaths under 1 yr old, per 1000 live births).
this means cuba does better than 200 other countries – worse than 43.
100 cuban ladies, over their lifetimes, would have 160 babies.

the czech republic has 1 death per 264 babies (14th place, 3.79/1000).
wealth, $26,100. fertility rate, 120 babies per 100 childbearing-aged woman.

singapore has the lowest infant mortality rate in the world,
with 1 death per 433 babies (2.31/1000).
[wealth, $54,000. fertility rate, 109 babies per 100 childbearing-aged women.]

the US, where the average wealth is $47,000 per year,
is 45th in infant mortality rate: 1 death per just 160 babies (6.25/1000).
that is 63% more infant mortality than singapore.
note, the per-person average wealth in singapore is only 12% higher than in the US.
cuba has 7% less infant mortality than we do, despite having only 20% as much wealth.
fertility rate: 100 american women of childbearing age would have 205 babies.
cuba’s fertility rate is 28% lower than ours, and singapore’s is about half of ours.

…if those 100 american ladies i mentioned, of childbearing age, were having their 205 lifetime babies in lane county hospitals, with the same rates as last year, only 137 of them would NOT have been born by cesarean. (8 babies – 6% of the non-surgical deliveries – would have been by forceps or vacuum extraction. so, really, only 129 would be normal births. i think we could do better…)

those sure are some interesting facts! but let’s go back to the science articles about the immune system.

what is “DNA methylation,” anyway?
it is a natural chemical attaching of a small, chemically ‘calm’ carbon molecule (“methyl group”), to part of a DNA chain. in some chemical diagrams, it looks like a little kite flying from the corner of one of the DNA blocks. it usually slows down or “silences” a gene. this is a normal, reversible process that is constantly occurring in all animals, plants, and even micro-organisms – “The methylation of [bacterial] DNA acts as a sort of primitive immune system, allowing the bacteria to protect themselves from infection” (yes, even tiny bacteria get sick – they catch viruses!).

and what are “white blood cells”?
they are immune system cells: macrophages (“big macs”), B cells and T cells (lymphocytes), granulocytes (they squirt grains of poison onto germs and parasites!), and also the white cells that go and live permanently in the tissues, such as the mast cells (also granulocytes, full of grains of histamine) that you notice when springtime allergies go crazy, making you sneeze and itch all the time (until you take an anti-histamine).

most of the research on DNA methylation is involved in preventing cancer, but some is directed at autoimmune disease, which is what the c-section authors were mainly looking at. in autoimmune disease (diabetes, asthma, MS, etc), the immune system mistakenly attacks the body’s own normal cells.

so how is this involved with the DNA methylation that the authors saw in the immune cells of the cesarean babies?
here is what some of the research tells us.

sometimes, for some reason, some white blood cells (T-cells) do not have enough methylation. because of this, they are less silent – they can’t keep calm – they become inappropriately reactive. normally, their job is to wipe out cells infected by viruses. but if they become overactive, everything starts looking like a virus-infected cell to them. for example, they might target normal insulin-producing cells (and cause auto-immune diabetes), or the cartilage in the joints (causing auto-immune “rheumatoid” arthritis), etc.

in the meantime, bacteria, which are naturally less methylated, induces more white blood cells (B-cells) to reproduce and get busy. lots of B-cell communities build up and make lots of antibodies that sugar-coat the bacteria, and the “big macs” come along and eat them. ultimately, the wreckage of destroyed bacteria, with their guts (chopped-up hypo-methylated DNA) floating around, cause a red alert in the immune system.

the red alert in the immune system makes a person feel sick!

here is a scientific example of how DNA methylation is involved in lupus:

“The T cells of [lupus] patients exhibit a lower level of DNA methylation compared with normal T cells, and this may be the cause of their inappropriate activation… An example of this phenomenon is offered by the treatment of T cells with 5-aza-deoxycytidine, an inhibitor of DNA methylation. T cells treated with 5-aza-deoxycytidine exhibit a low degree of methylation and undergo activation by the simple interaction with MHC molecules, even without specific antigen.”

[MHCs are "major histocompatibility complexes." but in plain language, they are like windows on the outside of cells, that display broken-up bits of protein. T-cells (or other white blood cells) window-shop to see whether the protein bits are normal-looking, or if they are bad-looking. bad, in this case, means, for example, from a bad virus, so then the T cell would start an attack on that cell. what the scientist here is saying is that under-methylated, over-aggressive T-cells go bonkers just looking at the windows themselves, ignoring what's actually displayed.]

the scientist goes on to say,

“Furthermore, hypomethylated microbial DNA shows a mitogenic [growth-producing] effect on B cells, while [normally methylated] vertebrate DNA does not… Thus, the DNA methylation level represents a distinguishing element between bacterial and vertebrate DNA. Accelerated apoptosis [cell death] with defective clearance may determine an elevated level of plasma-circulating nuclear antigen, which contains hypomethylated CpG-rich DNA fragments. These fragments may mimic microbial DNA and induce immune cell activation… as observed in [lupus].”

this means that the B-cells can tell bacterial DNA apart from our own DNA, by its fewer methyls. the various white blood cells, seeing bacteria this way, “attack” (or feast, or recycle, or however you visualize it). then, as i said before, the dead-bug goop floats around. if it doesn’t get cleaned up right away, it actually gives the appearance of even more bacteria being present (blobs of under-methylated DNA), causing an even bigger immune response – possibly resulting in the manifestations of lupus.

later on in the article, the author explains that sometimes specific infections and/or environmental exposures can cause a chain of events, partly involving DNA methylation, resulting in autoimmune disease. i guess i would posit that birth interventions may often fall into the category of “environmental exposures.”

BUT please recall i said a big BUT: complex organisms, such as mammals, are tremendously resilient. most of our immune system pathways are stunningly creative and heroically effective in keeping the whole ecosystem living together and co-evolving in relative overall harmony – human cells (skin cell to retina cell to stem cell to blood cell to bone cell), ‘partner’ cells (the vast array of normal flora living in our gut and on our skin, etc), ’sub cells’ (the mitochondria inside every one of our cells, which enable us to use oxygen for energy, distant cousins of the typhus germ!), and all.

so will your child who was born by cesarean become diabetic?
i hope not! for now, i think we have to trust our own flexibility and resilience; raise kids with the healthiest food, cleanest air and water, best sleep, and most liberty and justice possible; and reduce birth interventions to the absolute medical minimum.

i’ve been getting a lot of questions about immunizations lately, so stay tuned for part 2 – shots, immune systems, and you!

keep those cards and letters coming. (kidding!)

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