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Understanding foremilk and hindmilk

This was going to be a Facebook post to follow up on a statement I made in a post last week about frequently switching sides NOT causing an issue with foremilk/hindmilk. To read that post click here. But it ended up being too long, so I’ve turned it into a blog article.

For many parents the terms ‘foremilk’ and ‘hindmilk’ seem to have instilled a sense of dread – ‘oh you don’t want to do that, they might not get enough hindmilk’, ‘oh don’t do this, they might get too much foremilk’.

But what do the terms actually mean and do you really need to be concerned about them?

Technically the term foremilk means that it comes first and has traditionally been thought to contain a higher ratio of lactose to fat. Whereas hindmilk comes second and potentially contains more fat (although the milk contains the same amount of lactose regardless).

The terms foremilk and hindmilk in the world of human lactation are thought to have been first used in a 1988 research article that was used to explain why babies should be allowed unrestricted access to the breast (it’s possible the terms have been used in dairy industry for a lot longer). Up to the early 1990’s the prevailing advice for breast feeding was that the baby should ONLY be allowed to feed for 10mins on each side every 3-4hrs.

The authors concluded that babies who were restricted to timed feeds only got ‘foremilk’ and could be at risk of ‘lactose overload’, which may cause ‘fretfulness’ and ‘failure to thrive’. They believed that babies should be allowed unrestricted, untimed access to the breast.

However, 30+ years on (although as a Xennial, the 1990s were only 10 years ago!) society has demonised the words and lost the original reasoning behind using the terms.

According to an article by Nancy Mohrbacher (a world renowned IBCLC) the results of the first study have never been replicated and, although we still say babies should have unrestricted, untimed access to the breasts, it is now thought that the risks of ‘foremilk-hindmilk imbalance’ are more of a myth than anything to be too concerned about.

The truth is probably somewhere in the middle. But we are so used to seeing pasteurised and homogenised cows’ milk (basically the milk you see in the supermarket) and being bombarded with the message that we need to ‘fatten’ our babies up with fat, that we have a lot of anxiety around how ‘good’ our milk is.

The terms were first used in human lactation in 1988, explain why babies should be allowed unrestricted access to the breast.

I think it is important to understand that human milk is made perfectly for human babies. It is also important to understand that our babies need to be fed frequently throughout the whole 24hrs of a day.

Milk at the supermarket has been pasteurised and homogenised so that it does not separate.

Every 100mls of human milk contains just under 90% water, with approx. 7g of carbohydrates, 1g of protein, and 4g of fat, although the day-to-day (even hour to hour) composition may change according to environment and maternal diet*. Human milk can also be all sorts of different colours - if you didn't express you wouldn't know what colour it was...

Compare this to, say, cat milk which contains approx. 7g of carbohydrates, 8g of protein, and 4g of fat. Why? Because wild cats usually must leave their babies for longer periods of time while they go hunting, so they need more protein and fat, to fill them up for longer. On the flip side reindeer milk contains only 67% water and up to 18g of fat, maybe because they traditionally live in very cold climates where fat is needed to keep warm and being hydrated is not as important.

You see, the concentrations of water, lactose, protein, and fat in mammal milk depends on how the mammal parents look after their babies and what sort of environment they are raised in.

There are 4 classes of mammals – following, nesting, cache, and carrying.

Following mammals do just as the name suggests - the baby follows the mother around and include zebras, elephants, lambs, and cows. Nesting is also somewhat self-explanatory – the mother keeps the baby in a nest and include cats and dogs. Cache mammals hide their babies away while they go out looking for food and include rabbits and foxes, and they feed their babies very infrequently (sometimes only twice a day). These milks are high in protein and fat, as they need to keep the babies satisfied for longer.

Carrying mammals carry their babies with them and are the class that includes humans and other primates, they can feed their babies frequently around the clock.

If we could only feed our babies infrequently, like foxes or tigers or hyenas, or lived in very cold climates, like reindeer, our milk would be different.

But for our babies, water and lactose are the most important. Some fat is important for some bodily processes, but it is not vital to grow our babies.

Milk comes in many different colours and rations of lactose to fat - it's all good milk! (Thanks to my Facebook and Instagram followers for the photos, including Emsie, Kerrie, Jessica, Alana and Erica)

So why must we 'drain the breasts'?

The theory of why there is foremilk and hindmilk is that fat molecules are fatter and stickier than water and lactose and so stay behind in the breast for longer. When a baby feeds, the 'foremilk' comes first, with less fat. Then as they start to drain the breast, the fat molecules are squeezed out into the milk. If you limit the time and frequency at the breast, they might get less fat than what is possible. But remember, fat does not make the baby fat!

Think of it like your hot water taps – if you go to your tap and only turn it on for a brief moment, the water will most likely be cold. You need to wait for it to turn hot. But if you turn the tap off before that happens you might think there is no hot water. If you turn the tap on again quite soon it may start to turn warm more quickly. But again, if you turn it off before it turns hot and walk away, then come back hours later and repeat the process you might start to believe that there is an issue.

Normally what will happen is you turn the tap on, wait for it to turn hot, do whatever you need to do and turn it off. If you come back to it a few hours later, it may start off cold, but you know if you just wait it will turn hot.

On the other hand, if you let it turn hot, then turn it off and back on again quickly it will probably still be hot, or at the very least heat up much quicker.

It is important to understand that the breast does not make different types of milk, it just makes milk with various nutrients. We should not restrict how often a baby feeds at the breast and we shouldn’t time how long they spend at the breast, because we don’t know how long each individual baby needs to feed to get the right volume for them. And even if there is a thing such as foremilk, it is not bad – babies need water and lactose, otherwise they wouldn’t be the components that have the highest concentrations.

Humans are carrying mammals and our babies need to be fed frequently - allowing them untimed, unrestricted access to breast is best.

Draining the breasts frequently and well, will ensure the baby gets everything that they need. But if you have an oversupply, do not worry – just let the baby feed as often as they need, on each side as evenly as possible. If baby is not gaining weight as well as expected, but latching well, switching sides frequently in one feeding session can help them get more and drain each breast well (this may mean doing 4, 6, 8 or more sides in one feed). And NO, they will NOT get too much FOREMILK by doing this – I don’t know how much clearer or strongly to say this!

Some points to note:

Lactose overload can happen, but it is usually a secondary symptom of a protein intolerance, restrictive feeding, or very large oversupply. In protein intolerances (usually cow's milk or soy) the protein causes irritation to the lining of the intestine, which in turn can be irritated by lactose. To try to protect itself the intestine secretes more mucous and moves faster to try to get rid of the issue. If you are concerned that your baby has an intolerance, please see an IBCLC before 'diagnosing' you or your baby with anything.

*You cannot increase the amount of fat in your milk by eating more fat – your body decides how much fat your milk needs. What you can affect by the fat you eat, is the type of fat in your milk, so eat healthy fat, but there’s no need to go crazy with the amount. To increase the fat in your milk, let the baby feed as often and for as long as they want.

If you are due to have a baby, consider doing a breastfeeding and newborn class -

If you have a baby and need help with breastfeeding, get in touch for breastfeeding support (Medicare rebates apply up to 7 weeks) -


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