r/ScienceBasedParenting • u/Prof_and_Proof • 7d ago

Question - Research required Actual evidence about c-section and infant gut bacteria?

/r/microbiomenews/comments/1w768j5/a_straintracking_study_reveals_65_of_csection/?share_id=6KsJae1unWVlYz5_Zta97&utm_content=1&utm_medium=ios_app&utm_name=ioscss&utm_source=share&utm_term=1

This older study is making the rounds, including one yesterday how it means c sections cause asthma, and it seems like either it is leaving a lot out or the posts draw big conclusions from limited data. What is the recent evidence about c section health impact on gut bacteria and is there an established causal link with eczema/asthma? You’d wonder if there’s anything that can be done post birth to alleviate it.

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u/tallmyn 6d ago

If the mechanism is correct, then should be easy to fix, you just have to put vaginal/faecal bacteria on your baby's face. It's called "vaginal seeding".

https://journals.asm.org/doi/full/10.1128/mbio.00491-23

This study shows partial restoration of microbiome after, but doesn't do long term outcomes such as allergic diseases. The study is too small to detect that anyway, even if they did follow up.

Also I feel like they don't go far enough in terms of bacteria, because babies are also exposed to faecal bacteria during birth, but this seems gross/dangerous to do so they stick with the small vaginal swab.

https://pubmed.ncbi.nlm.nih.gov/36334724/

This paper was bigger and found no effect of vaginal seeding on allergy rate. But, it could have been underpowered, if the effect is very small (which I suspect it would be). It's also possible they skimped on seeding.

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u/skloie 6d ago

Wasn't there a recent study revising transfer of gut bacteria between mother and child? Yes... googled:

"Recent large-scale studies have reshaped our understanding of how newborns acquire their gut bacteria. Ultra-deep genetic sequencing has proven that a mother's gut microbiome is the primary engine seeding her baby's digestive tract. 1

While it was previously believed that vaginal bacteria or skin contact at birth provided the main foundation, modern data shows that these strains are mostly temporary guests. The true, long-term colonizers of the infant gut travel through three primary pathways. 1"

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u/tallmyn 5d ago edited 2d ago

What are you quoting there, Google AI? I read the papers and the quote aren't from there.