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Why is my Baby so Gassy? How much is normal and when is it a problem?

Babies are really gassy, aren’t they?  The frequency and the volume can often be a source of real amazement, humour and sometimes concern to new parents.  It’s definitely something that gets mentioned a lot in consults, and it seems that a huge panoply of behaviours are attributed to “wind” in this part of the world.  

Baby is bringing their knees up - they must have wind. Baby is straightening out like a board - they must have wind.  Baby is arching their back - they must have wind.  Blueness around the lips -  they must have wind.  Grizzling of any kind - they must have wind.  Sometimes I think we’re a bit pre-occupied with the whole idea of wind in babies.

Sometimes there is just a straight up mis-interpretation of a baby behaviour.  Newborn babies can really only do 2 core trunk movements - they can scrunch themselves inwards (flexing) or they can straighten /arch (extend), and they will do these movements for lots of reasons - to move position, to communicate they want to move, to say they want to swap sides, they want to feed, they want a nappy change, and on and on it goes.  Several times I’ve seen a baby pulling knees up to start a breast crawl from the position they are in (they will then cry if they don’t get to the breast), which was misinterpreted as wind.

That being said - babies do have wind, and lots of it, so I thought it might be good to talk a bit about it. 


What is Wind?

We should start with this very basic question, because I usually hear 2 different things being described as wind.  Some people will use “wind” to refer to air in the stomach which was swallowed during feeding i.e. the gas that gets burped up when you “wind” a baby after/during feeds.  Other people will use it to refer to intestinal gas which is ‘farted’ out (flatus).  Some people use the same word to refer to both, and some haven’t really thought about whether these are 2 separate things.  So let’s just look at them very briefly.

Swallowing some air is pretty normal.  We all swallow air, adults included and we normally release this later, often without really even being aware of it.  Babies will also swallow air while feeding, although how much may depend on how well they are attached to the breast or bottle, speed of milk flow etc, so some babies will swallow more air than others.  I find that a lot of people are worried about their baby swallowing air when in fact they are sealed well and just making normal feeding noises.  In her 2017 article which addresses swallowing air while breastfeeding, Pamela Douglas refers to ultrasound scans of babies and says that

Large volumes of air are not normally observed in the stomachs of breastfeeding infants

so there is likely not as much air being swallowed during breastfeeding as you may be worried about.  That being said, some babies struggle to make a seal for many reasons and can be taking in excess air - so if you are concerned about this, do see someone trained in assessing a breastfeed to check what is going on.  Some babies also struggle to seal well on a bottle, and that may be due to the shape/size/texture of the bottle teat or may be for other reasons.  Many IBCLCs can also help with looking your baby’s seal on a bottle teat.

Once some air is in the stomach it can potentially move 1 of 2 ways.  It can either be released up through the top of the stomach by burping, or some can potentially pass through to the intestines. The larger amounts of gas which is found in the intestines however is not likely to have come from being swallowed.  The gas is more likely to have been created in the intestine itself. This gas is more likely created by bacteria in the large intestine digesting and fermenting food particles (sugars from milk) and producing gas as the result of that digestion/fermentation.  This might seem problematic on first glance but is usually, in fact, a good thing as the bacterial colonies in our gut are a vital component to our health or lack thereof.


The microbiome

If you’ve read anything about the gut and/or gut health in the last 10 years you are almost certain to have read something about the gut microbiome / gut microflora / gut microbiota - which just refers to the microbial colonies in our gut.  Adults typically have as many bacterial cells in their bodies than human cells, and the lion’s share of those are in/around the gut, particularly the colon.  These microbial colonies establish a balance of different strains and species of bacteria - competing for space and keeping numbers of different strains in check.  This is why when you have antibiotics you are at risk of thrush.  Antibiotics kill helpful bacteria as well as pathogenic bacteria, and when the helpful bacteria are gone/reduced they are no longer keeping the candida (thrush fungus) numbers in check.  Candida colonies can then start to expand, causing thrush symptoms.  Once well established our balance of bacteria is pretty stable and unique to us as individuals - like a bacteria fingerprint.

Having the right bacteria in out gut is vital to our health.  Helpful strains help us to digest our food, they make vitamins for us that we are unable to make ourselves (Vitamin K) and they help to modulate our immune system.  Bacterial colonies have evolved with us to work together and keep us in good health.  Conversely when those microbiomes are out of balance, perhaps with more pathogenic bacteria in place then health is affected negatively.  The gut microbiome has been implicated in research in a mutlitude of chronic health conditions, e.g. ME / chronic fatigue (Giloteaux et al 2016), chronic kidney disease (Wing et al 2015), anxiety & depression (Wong eat al 2016), obesity [Ley et al. 2006b; Zhang et al. 2009], malnutrition [Kau et al. 2011], diabetes [Qin et al. 2012] IBS, Ulcerative colitis, Crohn’s disease (CD) [Frank et al. 2007] and cardiovascular disease (Hansen et al 2015).

So getting the right bacteria in place and creating a hospitable environment for the right bacteria is important.


Setting up the Microbiome

It is estimated that a 70kg adult male has 38000000000000 bacterial cells in his colon (Sender et al 2016).  This is where a lot of the fermentation and gas production will happen.  We are not born with these bacteria cells in place however.  A baby is born with a virtually sterile gut and the needed bacteria colonise the body in the days, weeks and months following birth.  Those bacteria come from the birth process (babies are designed to swallow mouthfuls of bacteria as they pass through the vaginal canal), the skin to skin contact we do after birth, from our family environments, and crucially - from milk.  Babies born by C-section may be seeded with slightly different bacteria than those born vaginally, and of course will be exposed to antibiotics during the surgery.  The type of milk a baby is fed will mean that different types of sugars are available to the bacteria for food and this alters the type of bacteria that will set up home in the baby's gut.  The type of bacteria which colonise the baby, in turn, affects the type of gasses that are produced, and potentially whether that gas is linked with discomfort and crying or not.

An interesting 2001 study (Jiang et al) looked at the types of gases present in the stools of babies who were either breastfed, cows milk formula fed, or soy formula fed, and found differences between the 3.  Six gases were quantified: hydrogen (H 2 ), methane (CH 4 ), carbon dioxide (CO 2 ), hydrogen sulfide (H 2 S), methanethiol (CH 3 SH), and dimethyl sulfide (CH 3 SCH 3).

They found that the breastfed babies produced the highest quantities of hydrogen (an odourless gas), and very low quantities of sulphur based gases like methanethiol or hydrogen sulphide.  This, conversely means that both groups of formula fed babies produced much lower quantities of hydrogen and much higher volumes of sulphur based gases.  This is significant not just because sulphur based gases both smell bad (and is why gas and poo smells very different in breastfed and formula fed infants), but the authors also note that,

these extremely toxic gases could irritate or damage the colonic mucosa.

They go on to say, 

H 2 S and CH 3 SH are highly toxic gases that can damage or irritate the intestinal mucosa. ... The colonic mucosa of the adult rat (and human) has a specialized detoxifying system that rapidly converts these sulfur gases to thiosulfate (29). This detoxification presumably allows the mucosa to protect itself from what would otherwise be injurious concentrations of the sulfur gases. In our study, levels of fecal sulfur gases of formula fed infants were similar to the values reported in adults, in which fecal H 2 S release is 1400 ± 182 nmol/g dry weight and CH 3 SH is approximately 530 ± 75 nmol/g dry weight (30). It is possible that the detoxification system for the sulfur gases may not be fully developed in infants and that irritation by sulfur gases might cause discomfort and/or play a role in certain intestinal disorders of infants.

So this is interesting I think.  Two points which I think are important for us to understand are:  

1. All babies produce lots of gas, and when you think about what is happening it makes sense why.  Babies need to very quickly get their gut colonised by bacteria to help it to function properly. It has to go from a either completely or virtually sterile gut to a gut teeming with bacteria.  Those bacteria are competing for space, multiplying rapidly and usually being fed a sugar rich fluid.  That sugar rich fluid is of course lactose in milk, but in addition to this breastmilk contains lots of special sugars called oligosaccharides which are there specifically to feed the right bacteria and help the gut get colonised with helpful bacteria.  These sugars are digested by the bacteria and gases are produced.  While the bacterial colonies are being set up there is going to be a lot of this gas production.  

2.  The milk diet that is given to the intestine will impact just what species of bacteria will thrive there, and that determines what kind of gases are produced and whether they smell bad or not and whether they might be toxic and harmful/painful or not.  It's not he only thing that will impact the species of bacteria - but it is a significant one.  This doesn't mean that all breastfed babies won't get some pathogenic bacteria in their gut.  Bacterial strains are shared in families, passed in birth, in skin, in our family environments and may be why allergies are 'vertically transmitted' from parents to children.  Many of us have our own gut problems, and may not have a perfect bacterial profile to pass on, nor was a perfect one passed to us, and we live in a world which is not very friendly to our good bacteria (chlorine in water, antibiotics in our toothpastes and foods etc).  What we do know from these studies however is that breastfeeding really does make a difference.  The special sugars in our milk really does make a difference to our babies gut and the bacteria that live there.  Breastfeeding gives our babies the best chance at a diverse, healthy microbiome.

The vast majority of babies will pass gas and not find it particularly painful.  They may grizzle at times, and may benefit from tummy massage or a soothing bath to help them pass gas and once they do they settle.  We’ve probably all had a little trapped wind from time to time and we understand that it can be uncomfortable, but the gas itself is usually just normal amounts and part of being a baby.

Some babies, however, are uncomfortable more often than is normal, crying abnormally and sometimes alongside their discomfort you may see frothy poo, bubbling with gas which smells unpleasant.  Colic is usually defined as a baby crying at least 3 hours a day for at least 3 days a week for at least 3 weeks in a row, and a number of studies have now identified differences in the types of bacterial species present in babies with colic and those babies without.

Babies with colic have less bacterial diversity in their guts and levels of Actinobacteria Bifidobacterium and Firmicute Lactobacilli bacteria specifically are inversely related to crying and fussiness - so less of these strains are correlated with more crying. The babies with colic also have more proteobacteria present (Dubois et al 2015).  Some studies using probiotics (helpful bacteria) as treatment for fussing and crying have also had promising results, like a 2018 study (Sung et al) which used the probiotic strain Lactobacillus Reuteri on a large group of breastfed babies which found that it reduced crying and fussing within 21 days.  They didn’t have as dramatic a result in formula fed babies, but there have been enough studies that many formula manufacturers are adding probiotics to their products.  The results of the study, of course didn't stop crying and fussing altogether - some crying and fussing is normal in babies.  Just like the rest of us, babies will have good days and bad days, and good and bad times of the day and times when they need help and support more than others.

So what does all this mean?  Well it means that babies really are gassy and that a lot of gas is very normal.  It’s part of normal digestion,  normal microbiome development and normal human development.  Gas and poos from breastfed babies should not smell bad, and that’s because the milk is feeding the right kinds of beneficial bacteria and although that produces a lot of gas - that diverse, healthy microbiome can be really important in future health.  So remember that the next time you are wondering about how gassy your baby is, and remember that a little bit of tummy massage can help everything keep moving along.



If you have any questions about a consultation or would like to arrange to meet, please get in touch.

Further Reading

1. Douglas, P. (2017). Making Sense of Studies That Claim Benefits of Frenotomy in the Absence of Classic Tongue-Tie. Journal of Human Lactation33(3), 519–523.

2. Giloteaux et al (2016). Reduced diversity and altered composition of the gut microbiome in individuals with myalgic encephalomyelitis/ chronic fatigue syndrome. Microbiome, 30.

3.  Wing et al (2015).  Gut microbiome in chronic kidney disease.  Experimental Physiology Vol 101 (4).

4. Wong et al (2016). Inflammasome signaling affects anxiety and depressive-like behaviour and gut microbiome composition.  Molecular Psychiatry 21, 797-805.

5.  Guinane et al (2013).  Role of the gut microbiota in health and chronic gastrointestinal disease:  understanding a hidden metabolic organ.  Therapeutic Advances in Gastroenterology.

6.  Hansen et al (2015).  The gut microbiome in cardio-metabolic health.  Genome Medicine, 7 (33). 

7.  Sender et al (2016).  Revised Estimates for the Number of Human and Bacteria Cells in the Body.  PLoS Biol 2016 Aug 14(8).  10.1371/journal.pbio.1002533

8. Jiang et al (2001).  Gas Production by Feces of Infants.  Journal of Pediatric Gastroenterology and Nutrition Vol 32 (5)

9. Sung et al (2018).  Lactobacillus reuteri to Treat Infant Colic:  A Meta-analysis.  Pediatrics Vol 141/Issue 1

10. Dubois et al (2015).  Characterizing the Intestinal Microbiome in Infantile Colic:  Findings based on an Integrative Review of the Literature.  Biological Research for Nursing Vol 18 issue 3, pages 307-315.



About the author

Carol Smyth

I am an IBCLC (International Board Certified Lactation Consultant) in private practice in Northern Ireland and a La Leche League Leader with La Leche League of Ireland

Important Information

All material on this website is provided for educational purposes only. Online information cannot replace an in-person consultation with a qualified, independent International Board Certified Lactation Consultant (IBCLC) or your health care provider. If you are concerned about your health, or that of your child, consult with your health care provider regarding the advisability of any opinions or recommendations with respect to your individual situation.