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Why Your Microbiome is Older Than You Are.

Now we know. A baby’s microbiome starts developing in the womb.

You probably wonʼt remember this, but the very first poop you popped out as a baby was pretty extraordinary.

So extraordinary, in fact, that it even had a name.


A babyʼs first bowel movement consists of stuff that was already in the gut before the first meal.

And Meconium is like no other stool youʼll ever pass.

Itʼs kind of dark olive-green with a tarry, viscous consistency, barely any smell, and made up of stuff you ingested when you were in the womb, including skin cells and “lanugo” – that thin downy hair often found on an infantʼs body.

Delightful, right?

But thatʼs not all meconium is made up of.

Researchers at the University of Florida discovered in 2010 that new-born babiesʼ meconium contains a diversity of bacteria, and that came as something of a shock.

You see, back in 1900 a French pediatrician called Henry Tissier had confidently declared that unborn babies were bacteria–free.

So according to popular myth, a baby was effectively sterile until the moment of birth.

Now to be fair to Tissier, he also isolated and named a bacterium called Bifidus that went on to play an important part in the world of probiotics, but thereʼs no doubt that he caused over 100 years of microbial misunderstandings with his sterile baby theory.

However, while itʼs certainly true that babies are born with a certain amount of bacteria, most of their microbiome builds up over time, with the first few minutes of life being especially important.

If a baby is delivered vaginally, she receives a dose of bacteria from her mother as she passes through the birth canal, getting covered in a microbial film that includes species which will help her digest her first meal.

But what happens if she enters the world as a result of a Cesarean section?

Well then her first dose of bacteria is likely to come from her motherʼs skin rather than her vagina, an observation supported by a Swedish study which showed that babies born via C-section have gut bacteria which show significantly less resemblance to their mothers compared to those delivered vaginally.

Some parents restore the balance after C-sections by “inoculating” their babies with a vaginal swab: incubating a piece of gauze in the vagina for an hour prior to delivery, then wiping it over the mouth, face, and body of the infant after delivery, in a process sometimes called “seeding”.

Quite a wake-up call.

A babyʼs microbiome continues developing after birth, resembling that of an adult by the age of three.

In fact babies pick up microbes from every single person and thing they touch, which in general is A Good Thing.

Humans tend to do best when they play host to a diverse microbial community.

A University of Idaho study found that there are even important bacteria in breast milk, meaning that the guts of babies given formula differ from those fed on breast milk.

All in all thereʼs no doubt about it.

Your bacteria play a vital part in your health, and always have.

Ever since you passed that rather outlandish first poop.

Have a great week!
Alexandra :)

Alexandra Carmichael
Director of Community, Product, and Growth

Further reading

Your Changing Microbiome

Nurturing A Babyʼs Microbiome, Before And After Birth

The Maternal Microbiome

Maturation of the Infant Microbiome

Human Microbiome May Be Seeded Before Birth

The infant gut microbiome: New studies on its origins and how it’s knocked out of balance

The Human Microbiome, Diet, and Health: Workshop Summary

How to seed your baby with a healthy microbiome to last a lifetime

Mothers facing C-sections look to vaginal ‘seeding’ to boost their babies’ health

Microbirth: Why ‘Seeding Baby’s Microbiome’ Needs to Be on Every Birth Plan

Intestinal Microbial Ecology in Premature Infants Assessed Using Non-Culture Based Techniques

Characterization of the Diversity and Temporal Stability of Bacterial Communities in Human Milk

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