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Tuesday, March 5, 2013

What expectant parents need to know about baby's gut bacteria

Expectant parents, tell me this:

If there was a thing you could do for your child that might decrease his or her chances of being obese, suffering from asthma, or developing type 1 diabetes later in life (and possibly more)... how hard would you try to do it?

Well, there is a thing. And that thing is protecting the little one's gut bacteria, right from day one. 

When I was expecting my daughter, I was already a full-on gut bacteria geek. Instead of reading What to Expect before bed, I was downloading studies on the gut bacteria of newborns. Oddly, the topic was nowhere to be found (outside the scientific literature) in my pre-baby immersion experience. I don't remember a single mention in the parenting books, blogs, prenatal groups, or even my medical professionals.

Luckily for all the babies yet to be born, that silence around gut bacteria will definitely change over the next couple of years.

How do I know? Because the science that's already out there says that gut bacteria is highly relevant to both labour and newborn care. Health outcomes later in life may have everything to do with those couple of days leading up to birth, and with the birthing process itself. It's not just an exercise in getting the baby out. It's the challenge of getting the baby out with good gut microbiota intact. This microbial garden is so important that microbiologists are starting to think of it as the baby's "forgotten organ". Not sure about you, but I would certainly want my baby delivered with all of its organs included.

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In a nutshell, these are the things that can have an impact on baby's gut microbiota:

1) Mom receiving antibiotics before and during labour
2) Baby born by caesarean section
3) Baby breastfeeding
4) Baby receiving antibiotics early in life

Even in the past year, researchers have started to put more empirical data behind these. A few of the above started out as mere theories, but now there is evidence for each one of the four factors.

One recent Canadian study that investigated factors 2 and 3 above was called Gut microbiota of healthy canadian infants: profiles by mode of delivery and infant diet at 4 months, published in the Canadian Medical Association Journal. With 24 subjects, the study is big enough to be interesting, though small enough to warrant continued research.

The study was basically a snapshot of gut bacteria at a single point in time - 4 months - along with information on the infants' birth and health histories. Researchers found that all kids had certain bacteria in common (e.g. Bifidobacteria), but there were some important differences:

Vaginal birth vs. Caesarean section

Certain bacteria were "underrepresented" in all infants born by c-section, as compared to those with a vaginal birth: those of the genus Escherichia–Shigella. And one entire phylum of bacteria (Bacteroidetes) was absent from the c-section babies.

Elective caesarean section vs. Emergency caesarean section

Here is an interesting one - the researchers found that the gut bacteria of those born by elective c-section had the least richness and diversity of all groups. Leaving aside the question of whether low richness and diversity is a bad thing, it could be that elective c-sections result in different intestinal bacteria than emergency c-sections, which happen after a woman's body has initiated labour. Researchers are intrigued, but not yet sure why this could be the case.

Breastfeeding vs. Formula

A difference here should be no surprise, since breastmilk is full of great bacteria. Even the fancy probiotic formulas can't do exactly the same job. The breastfed babies had significantly higher numbers of 2 families of bacteria (the eloquently-named Peptostreptococcaceae and Verrucomicrobiaceae). Formula-fed babies had more richness and diversity, meaning that the breastfed babies had fewer overall species present and that certain species tended to dominate in the gut. Notably, babies on formula harboured more C. difficile.

The data in this study is descriptive, and the researchers left out the weighty question of what kind of intestinal garden is better and what's worse. See, we don't yet know what the ideal gut should look like at 4 months, so we don't yet know what a poor gut looks like, either. All 24 infants were healthy, so in some sense the data all describe the range of normal. But judging by other research on health outcomes, it's fair to say that whatever the vaginal birth and breastfeeding do to the babies' gut bacteria, it's a good thing.

I was happy to see this study reported so widely in the media when it was published in February. There were several great articles on it, including one by Paul Taylor in The Globe and Mail.

I did shake my head, however, at one misleading line that was meant as a caution:

"Canadians seem to be opting for c-sections in increasing numbers. "

As I outlined in a series of tweets, the (limited) data show that women are not at all "opting" for c-sections.

The increasing c-section rate is likely because of more emergency c-sections - which has to do more with the decision-making of surgeons rather than mothers. A study right here in British Columbia, a place with one of the highest c-section rates in Canada, found fewer than 2% of those surgeries were a result of maternal request. (Incidentally, collaborative maternity care in B.C. has been shown to reduce the number of c-sections.) 

There's one other thing I have to address with this study. That's the anxiety of parents who have already birthed their bundle in a situation where things weren't exactly optimized for great gut bacteria. I know more than a few people in that boat.

Not to worry. There are things you can do later in life to keep your little one's garden growing well. Some of my other blog entries explain what these are (here and here, for example).

And if you are a parent-to-be who really really hopes you can protect that baby's gut bacteria on the important day that it decides to enter the world, I want to share the best piece of wisdom I got before the birth of our little girl: "Labour is like a box of chocolates. You never know..."

Which means, you can't control everything all the time. Least of all a brand new, squirmy human, a mother's wonderful and wise body, and teams of midwives and doctors and nurses. You may indeed end up having a c-section and unable to breastfeed. But simply by being aware of the factors that affect baby's gut bacteria, you can take steps to nurture it as best you can.


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  2. Hi Kristina,
    My daughter, now 3 months, was born by c-section after a 44hr labor because, sadly, there simply wasn't another way for us. Following the delivery, which logically included IV-antibiotics for me, we were forced to partially supplement breast feeding with formula for several days when her birth weight dropped too substantially. I took probiotics within days of the delivery, as soon as I was home from the hospital, in hopes of boosting her healthy gut flora. She is now displaying digestive issues that doctors have attributed to intolerance to proteins (dairy and soy, most prevalently) in my breast milk. I have begun to suspect a connection between these intolerances and her gut flora, or lack thereof. Would you agree with that theory? And what would you suggest I do, when yogurt is not an option for us? Thanks!

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