Caesarean babies have different gut bacteria, microbiome study finds | Hacker News Reader

Caesarean babies have different gut bacteria, microbiome study finds

theguardian.com

199 pointsuxhacker137 comments

This has been known for quite a while, basically passing through the non sterile vaginal canal vs the sterile (or close to it) abdominal wall yields differences. This has lead to some questionable practices such as "vaginal seeding" whereby new moms will swab their vagina and then seed their babies shortly after birth (usually through placing the gauze in babies mouth or around their face). This comes up not infrequently at the hospital I work at. I think much of it stems from Facebook rather than actual discussions with their OB.

Michael Pollan wrote [1] about an evolutionary biologist who did this exact thing after his daughter was born via cesarian.

[1] https://www.nytimes.com/2013/05/19/magazine/say-hello-to-the...

Well, what was known is wrong. The original hypothesis was the bacteria came from the vagina, but this study shows it comes from gut.

The article addresses this practice and states that the bacteria found in babies born vaginally differs from the bacteria found in the vaginal canal this further calling into question this practice. The bacteria instead seems to come from the mother's gut.

Specifically, it comes from faecal matter that she expels during the birth.

There is scientific rationale for this, from one of the top medical journals:

https://www.nature.com/articles/nm.4039

This article is about new research that says the source of useful gut flora is not the vaginal canal, but is in fact from faecal matter from the mother.

My younger brothers are identical twins, one born vaginally and the other 20 min later via C-section. I've always said they'd be good data for these type of studies.

Anecdotally, they don't really have big differences regarding allergies or autoimmune disorders. Although growing up I always complained one stunk up the bathroom worse than the other.

I think you were just trying to divide and conquer. It's hard to compete with twins! ;)

Which is the stinker?

C-section. n=1

Wouldn't the other twin be n=1 as well?

Any idea how frequent this (the first naturally, the second via C-section) is ?

Well, it would seem that when it does happen it’s a 50/50 split

Increasingly in developed countries twin births are caesars; the risk profile of twin births often necessitates this for patient safety.

When a normal vaginal delivery is possible (ie first twin cephalic) generally the second will follow. My partner (obgyn Resident ) says she has had 2 twin births where the first was vaginal and the second Caesar, out of roughly a couple hundred

This has been hypothesised for a while and is listed in many pregnancy books. There are also hypothesis linking the difference in gut flora to other long term outcomes (obesity, autism etc) in adults.

Reference:

J. Neu and J. Rushing, “Cesarean Versus Vaginal Delivery: Long-Term Infant Outcomes and the Hygiene Hypothesis,” Clinics in Perinatology 38, no. 2 (2011): 321–331.

My twin brother was born by caesarean. He gets asthma attacks from allergies that I don’t have. I’ve wondered for a while what effect a faecal transplant could have...

Had he had a skin test done to see what all he is allergic to?

He may be able to get allergy shots to help treat allergies.

I thought allergies are built up over time and so vary greatly with individuals, a perfect sample of the "nurture" side of the coin. (Though I'm sure you can have genetic predispositions.)

Here is one thing that came up after googling: https://www.nytimes.com/2003/11/25/science/q-a-twins-and-all...

> In other studies, asthma, which is often tied to allergies, showed up in both identical twins only 20 percent of the time.

This is something that his doctor should be concerned with.

The idea that there is some doctor who will employ the latest and greatest of medical research to take care of me is at odds, to say the least, with my experience in the healthcare system.

If you decide to do this, please document heavily and report back on results.

Anecdotally, I am Norwegian genetically, and it has been said that the scandanavians are the group that developed the gut biome to be able to eat cheese/dairy - and I eat a TON of cheese each year (and I suffer no ill affects (I’m super lean and tall and skinny))

Whereas one of my exes was Asian and would get IBS whenever she ate cheese.

> group that developed the gut biome to be able to eat cheese/dairy

Why would one need to "develop" a gut biome to eat cheese/dairy? Have you ever heard of breast-feeding? Yes, you may be surprised to hear that even Asians can breast feed.

What you seem to be thinking about is lactose intolerance, which is not due to a gut biome issue but due to genetic or environmental factor causing a deficiency of lactase, a protein, after infancy. Lactase persistence is not common in many ethnic groups.

There is evidence that a biome habituated to certain strains of lactobacillus can allow those that would otherwise be intolerant to become tolerant, but that has nothing to do with the cause of lactose intolerance.

> Whereas one of my exes was Asian and would get IBS whenever she ate cheese.

IBS is a functional digestive pain syndrome. It has nothing to do with lactose intolerance. For someone epeening about their medical knowledge, you seem to know very little to back it up.

Sure dude:

adult lactase persistence in ancient skeletons in Northern Europe, Scandinavia, southern France and elsewhere.

https://www.npr.org/sections/thesalt/2012/12/27/168144785/an...

What are you trying to say? How does this contradict anything I just said?

Lactose intolerance is an issue involving lack of endogenous proteins, not the gut biome.

Asians, all humans, except for rare cases can digest lactose in infancy.

IBS is a functional gut pain/dysfunction syndrome. Those with lactose intolerance don't get IBS when they eat cheese.

Children create lactase to process milk (lactose) until around puberty, then they stop creating it. I learned in college that studies have shown that a lot of people of Northern European descent continue to create lactase into adulthood, and thus can continue to break down milk and cheeses without issue.

There is still a percentage of non-European population that can consume lactose into adulthood, and not break it down without any external symptoms.

There are plenty of non-Europeans that can digest lactose. Think middle-easterners and Mediterraneans and their consumption of sheep and goat milk. Central and East africans too. The trait has incomplete (variable) penetrance.

Lactose tolerance is estimated at 30-45 percent.. So it's a substantial non-European population. The intolerance is heavily skewed toward East and South Asia -- though a lot of South Asians consume milk and paneer.

As a guy with a brother, I can't help but read this as yet another ploy to get one-up on the brother, but this time in the name of science!

I was under the impression that this has been pretty well established for a while.

Came here to see if I was going crazy or if others had also heard of this before.

Is this about new findings? Or just a regurgitated set of findings to get into the press? The article isn't clear as far as I can see.

Here is a link to the study the article references published today: https://www.nature.com/articles/s41586-019-1560-1

Yes, before it was believed that the bacteria came from the vaginia, but now it looks like it comes from the gut.

I thought the same. Our OB/GYN, doula, hospital staff and birthing classes all covered this as if it were factual and provided some ways to overcome it should you go through a c-section.

Still good to see studies around this get passed around. You never know if you'll have to go through an emergency caesarean and being prepared is best.

Yes, it is currently normal but not universal to take a vaginal swab from the mother and rub it in the newborn's mouth. Not a new idea at all.

> “In many cases, a caesarean is a life-saving procedure and can be the right choice for a woman and her baby,”

And in other cases it is a way to make life easier for medical staff?

Here in Panama, babies are disproportionately born through C-section in privately run hospitals.

Update: While I can't cite any stats for Panama, there is an article [0] that says

"The rates can be even higher in private clinics. For example, in Brazil, 80-90 percent of births in private clinics are now C-sections, compared with about 30-40 percent of births in public hospitals."

[0] https://www.npr.org/sections/goatsandsoda/2018/10/12/6561984...

Joshua Gans (my old economics Prof) did a study of births by day of week, and showed that the fall in weekend births was explainable by the rise in inducement and cesarean section procedures.

https://www.academia.edu/2808187/What_Explains_the_Fall_in_W...

"To posh to push", was also a saying a generation ago.

In Dutch the C-section is called the "King's cut".

Sorry for nitpicking: "emperor's cut"

Named after emperor Caesar, just like the word "caesarian".

I wonder, does this relationship hold at 1 month old? 1 year?

Any decent longitudinal studies of C-section babies from elective sections removing the health based ones?

Having a c-section might not be the underlying cause of the problem. Doctors carry out c-sections when a vaginal birth would create complications for the mother or the child. I.E. the mother or child was already "sicker" prior to the c-section.

I'd love to see a randomized control trial for this. To do it ethically, the trial could be designed like the CRASH trials. In those trials, doctors received patients with head injury and administered a placebo or corticosteroids. Since it was unclear whether corticosteroids helped or hurt, it was ethical for doctors to randomize patients. For births, only situations where it's 50/50 between a c-section and vaginal birth would qualify. Perhaps it's too small a subset to be workable or perhaps it's never 50/50, but that type of trial would provide much stronger evidence for this intriguing idea.

On a personal note, I was a c-section baby and seem OK!

> the mother or child was already "sicker" prior to the c-section

That is your illusion.

TL DR: C-section babies pick up more hospital bacteria than those born vaginally, research shows. The findings could explain the higher prevalence of asthma, allergies and other immune conditions in babies born by caesarean. By six to nine months, the differences between the two groups had levelled out. But scientists think that the initial exposure to bacteria at the moment of birth could be a “thermostat” moment for the immune system, defining its sensitivity and which strains of bacteria trigger a response.

Please don't tldr if you're going to do it this poorly.

The new bit of this story is that the vaginal canal isn't adding anything to the microflora of the baby, and that the source is in fact fecal matter from the mother during birth.

The biggest question that surround all this microbiome discussion is - does the difference even matter?

Note that you can significantly alter your gut microbiome simply by changes to your diet.

Right now the link between the microbiome and allergies is tenuous at best.

My understanding is that yes environment makes a huge difference in your biome, however there may be strains of bacteria, for example, that you would only get from your mother. Maybe something she picked up playing in the dirt in a different country, or maybe something from her mother.

Whether it makes a difference really depends on the individual. Personally I think it's better to get the gut bacteria that you can from your mother near the time of birth, but that's me.

If you were to test the microbiome of a family, you’d find they are very similar. Humans living in close quarters exchange biomes readily (oral - fecal transmission).

I’m certainly not arguing there is no impact of the microbiome on disease, but right now the data is far to early to say anything conclusively.

> does the difference even matter?

The article seems to say the answer is yes:

...scientists think that the initial exposure to bacteria at the moment of birth could be a “thermostat” moment for the immune system, defining its sensitivity and which strains of bacteria trigger a response.

I was depressed for half my life, I read on gut microbiome about 5 years ago(swapping the gut microbiome of mices changes their character) but didn't put it together until I switched my diet to meat only. Any kind of sugar seems to trigger depression for me, that sadly means that I can't eat plants. And current push for plant based diets worries me a lot. I was a C-Section baby.

Eating only meat is a serious health risk.

There are other sources of protein, and many vegetables that go very well with a low carb diet.

just like I said, the moment I eat anything containing fiber or sugar, depression comes crashing back. Making me want to die and stuff like that.

> Eating only meat is a serious health risk

[citation needed]

You can’t eat spinach or broccoli?

nope

Gut bacteria IIRC effect personality/mood as well as other things.

the mother probably gets antibiotics before caesarean. Does that antibiotic make it into the baby? That would mean that beside not getting the good vaginal mix of bacteria (that mix among other benefits seems to be able to control candida yeast growth which is a big deal on its own), the bacteria set that the baby already possesses gets hit by the antibiotic, a double whammy of sort.

A Caesar mother does get a stat of antibiotics before opening. In crash caesars this would barely have time to distribute; normal operating procedure calls for the dose to occur 30 min to 1 hr before skin incision though.

You have a bit of a misunderstanding here - a baby does not have a microbiome in the womb - it is a sterile environment

>You have a bit of a misunderstanding here - a baby does not have a microbiome in the womb - it is a sterile environment

no. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4350424/

"The first, and most important, contribution to the genesis of the microbiome is vertical transmission of maternal microbiota. Colonization of mucosa in the digestive, respiratory, urogenital tracts, as well as the skin begins at, or perhaps even before, the time of birth when a newborn is exposed to a mother’s microbiota. It was previously thought that the in utero environment was largely sterile and that a fetus was not colonized with bacteria until the time of birth. Recent studies suggest the presence of a microbiome within the placenta as well as fetal meconium, suggesting that the colonization process begins well before delivery. "

And my point is that the "most important, contribution to the genesis of the microbiome" probably gets hit with the antibiotics given for C-section.

Thanks. This is new knowledge since I was at medical school.

The paper you link however is not at all convincing.

A better paper here: https://www.frontiersin.org/articles/10.3389/fmicb.2019.0112...

Does a better job of explaining things. Interestingly the species isolated are highly homogenous - https://www.frontiersin.org/files/Articles/454989/fmicb-10-0...

Most samples had only a single species isolated from meconium; Controlling for sources of contamination it looks like out of the sample of 43 there were several that would meet the classification of a sterile environment.

So, I was wrong; but so are you

I'm not insisting on specific source of bacteria. I mentioned it only as illustrative detail/example, and it only distracted (who knew that here would be a medical professional for whom getting such details right is naturally important - the same way like it is very distracting for coders when movies get computers related details wrong :) from the main point that baby coming out of C-section may have antibiotics in him/her which would screw with whatever gut microbiome "priming" scenario pre-/post- delivery he/she would be going through.

I take your point but it’s not binary - in the sense that I have strong doubts that the MIC (Minimum inhibitory concentration) of antibiotics would touch much of a colonisation in a neonate should it be present.

Having a single dose of abx in an adult doesn’t kill everything; the intent of a pre-surgical dose of abx is because evidence shows it significantly reduces post op infections; and the antibiotic used is active primarily against gram positives (cephazolin 1-2g) whereas Pelomonas puraquae is a gram negative anerobic rod and more than likely not going to be touched, even if the MIC is reached (and my experience of obstetric theatres is the antibiotic usually (80% of the time) goes in only minutes before skin incision.

So; a couple of things:

- presuming no contamination in the study, the primary coloniser of neonates appears to be a gm -ve rod

- antibiotics given for caesars are active against gm +ves /aerobes

So while there may be a mechanism, it’s not highly plausible in light of the other known mechanisms affecting Caesar births vs natural (ie bacterial microbiome pickup during traversal of the birth canal) about which there is significant evidence regarding immune priming

This is old news.

I thought the same, but No, as the original hypothesis was the bacteria came from the vaginia, but this study shows it comes from gut. It maybe because during delivery women often have anal fissures.

I am not an obstetrician but I am pretty sure that fecal transfer is far more likely because of acccidental pooping while 'pushing' instead of anal tearing/fissures.

Oh God. How did I get here.

Many of us Caesarian babies didn't get "vaginal seeding" at birth, but have been trying to catch up ever since.

You joke, and are being downvoted, but I had never ever thought about cunnilingus affecting ones gut biome. Is that ridiculous or even possible?

It certainly affects gut biome, personal observation and what I've read. Michael Douglas also believes this caused his cancer.

It's a cliche that the kids from the rich side of town, who didn't put dirt in their mouths growing up, are the ones who get mono in college. Farm kids are healthiest; our immune systems need regular work they can manage.

Cancerlingus?

Preposterous.

HPV can cause mouth and throat cancer[1].

[1]https://www.nhs.uk/live-well/sexual-health/can-oral-sex-give...

So that would be HPV causing cancer. Not cunnilingus. If you are insinuating that the transmission of HPV is through cunnilingus then fine. But stating a direct causation is careless.

So that would be the impact causing injury. Not stepping in front of a car. If you are insinuating that the impact was caused by stepping in front of a car then fine. But stating a direct causation is careless.

everyone here is insinuating that the transmission of HPV is through cunnilingus in this context

Ask yourself, why are you missing this context or being intentionally obtuse? you aren’t smarter or deemed as smarter for pointing out the obvious that other transmission methods are possible, everyone already knows that and is still enjoying these euphemisms because of their relatable conscious decision to give head. Curious what the thought process was here

> Farm kids are healthiest

Why can't we just buy some farm dirt in pill form?

Because it's easier and more effect for one to just go outside.

My sister works as a physician at Phoenix Children’s Hospital and they are literally studying whether giving “dirt pills” to children helps prevent asthma. Wish I could find the link for more info.

Coronado Biosciences tried to treat Crohn's disease using hookworm eggs. Basically give the patient a bunch of eggs, the hook worms hatch, cause an immune response, then die (as they can’t live in humans).

Clinical trial showed no impact at all on the disease.

I think you mean to say they can't, but… they can https://www.cdc.gov/parasites/hookworm/gen_info/faqs.html

I did mean “can’t”.

Coronado used porcine (pig) hookworm eggs that’s can’t complete a reproductive cycle in humans.

A great idea for a startup.

It's a cliche that the kids from the rich side of town, who didn't put dirt in their mouths growing up, are the ones who get mono in college.

This is true but not necessarily for the reasons you think. Epstein-Barr is largely harmless in younger children, showing up largely as a common cold. It's not that the "farm kids" didn't get infected; it's just that they were infected long before they got to college.

(And to preempt a common question: No, we shouldn't proactively expose kids to Epstein-Barr when they're young. While they wouldn't get mono, Epstein-Barr has other long term effects; for example, it has been implicated as a trigger for autoimmune disorders.)

Michael Douglas’ cancer was caused by HPV - a Virus not a bacteria. HPV is a well known oncogenic Virus

Yeah but he jokes about it being from cunnilingus

More than likely that is how he caught it - but it is not a bacteria

Jamie Dimon had throat cancer and the first thing I thought of was him eating some ladies out

I paid for my HPV vaccine out of pocket while the money was good, with the risk of it being completely ineffective at my ripe old age of 26

Does he smoke cigars? Throat (and mouth) cancer is common in cigar smokers.

Perhaps. HPV was also linked to throat cancer. It requires contact with HPV, and is one of the only ways HPV directly affects men, because they put an HPV infected part of the body in their mouth.

Not here to debate probabilities, but it is interesting how the possibility is controversial to some

Michael Douglas had hpv+ SCC throat cancer. Hpv is a virus, has nothing to do with the gut microbiome as it is commonly discussed and is the cause of cancers of the cervix and head and neck. The oncogenic varieties are sexually transmitted. So he’s right.

not ridiculous — it leads to higher chances of throat cancer, tragically, thanks to certain viruses being picked up in this manner. (I know, viruses and bacteria are not the same, but they share transmission vectors)

Another thing you might never have thought about, but might be real (subject of recent and ongoing research): women incorporating DNA from men's sperm into their bodies. Search "microchimerism" with "sperm", e.g. [1]. (There's probably more instances of "sharing DNA from close encounters", but this one is particularly easy to research simply by checking for Y chromosome in women's bodies.)

[1] https://www.ncbi.nlm.nih.gov/pubmed/27623703

That's interesting. This is totally off the wall, but I've noticed that many long time couples start to look like each other. I've assumed it was from environmental factors, but what if there was some biological basis as well? Crazy to think about.

> I've noticed that many long time couples start to look like each other.

Even if they're not from the same ethnic group?

In later life a fecal transplant may be required.

For a second there, I thought I was on a different site!

This is by far the most hilarious comment I've seen on HN!

Reply on news.ycombinator.com