Foremilk and Hindmilk – are there two different kinds of milk?

As a breastfeeding mum, you may worry, ‘is my baby getting enough milk?’ Then there is the pressure, usually from older women, that there is no ‘goodness’ in your milk if your baby is unsettled or feeding more frequently than they feel is ‘right’.  You may have heard about foremilk and hindmilk, so these comments can undermine your confidence and have you questioning whether your baby is getting enough ‘fatty’ hindmilk.

Firstly, there are good signals that your baby is getting enough milk apart from appropriate weight gains and wet and poopy nappies (what comes out must have gone in) to hearing him swallow as he feeds and watching his jaw - see the muscles in front of his ears as he sucks rhythmically and how his chin drops down as he sucks in milk, just as your own chin drops down as you drink from a straw – long steady sucks indicate good mouthfuls of milk.

So, what is the difference between foremilk and hind milk?

As your baby starts sucking, or you begin to pump milk, the milk that has collected in the large ducts or milk sinuses directly behind the nipple will be removed.  This first milk which is higher in water content is the ‘foremilk’, while the higher fat milk in the smaller ducts and alveoli, higher in the breast that is released to your baby by the ‘letdown’ or ‘milk ejection reflex’ is the ‘hind milk’.

Not only will your baby receive a good flow of milk as your milk lets down, but this reflex will be squeezing the higher fat milk that adheres to the sides of the alveoli down to your baby too.

It doesn’t mean there are two types of milk or that your baby will reach the ‘hindmilk’ at a particular time during a feed: consider how, when you have a cold tap running and you turn on the hot tap, the water gradually mixes from cool to warm. This is a similar process as the higher fat milk is made available to your baby as your letdown is activated and your milk flows to your baby as he feeds.

How does the letdown reflex work?

Imagine the inside of your breast looking like a bunch of broccoli – with your nipple on the end of the stalk and the florets being the cells inside your breast. Higher up in your breasts, there are milk secreting lobes (the clumps of broccoli florets). As your baby starts to suck, the stimulation of the nerves in your nipple trigger the release of the hormone oxytocin. This causes cells around the milk secreting alveoli (the tiny buds of broccoli) to contract and duct passages (stems of each broccoli floret) to widen, pushing milk down into the sinuses behind the nipple. This is your ‘letdown’ or ‘milk ejection reflex’ at work.

How do I make sure my baby gets the ‘best’ milk?

Firstly, all breastmilk is amazing, there is no such thing as ‘poor quality’ milk or milk that isn’t ‘strong enough’. There are important nutrients in both foremilk and hindmilk. 

Your foremilk matters - that 'watery' milk contains protein and lactose, the main carbohydrate. Lactose is important for brain growth in the first two years as your baby's brain development is so rapid. It's especially important for the development of the myelin sheath that protects and insulates the nerves in our brain and spinal cord and allows electrical impulses to transmit efficiently along nerve cells. Lactose also influences your baby's gut health, supporting the growth of beneficial bacteria and it helps with the absorption of calcium and phosphorous important for bone development. 

Ditch the worry about fore milk and hind-milk

As long as you watch your baby’s feeding cues, you can trust her to take exactly the amount of milk she needs in the consistency that she needs for growth and development.

For instance, on hot days, your baby might have more shorter feeds because he needs the more ‘watery’ fore-milk to quench his thirst (he doesn’t need water, this can be unsafe for babies under six months). At other times, he may have a longer feed to satisfy hunger, as the fat content increases through a feed.

In the evening, your baby might ‘cluster feed’, having more feeds closer together. You don’t need to worry that your milk supply is reduced, or that your breasts feel ‘empty’ (milk production speeds up as your breasts ‘empty’).

According to research from the Hartmann centre in Western Australia, milk volume is not low at this time of day. Even if milk volume is lower in the evening, fat content is typically higher (particularly if baby is allowed to control this via cue feeding), so the amount of calories that baby is getting should not be significantly different. 

Watch your baby, not the clock

Remember the analogy about turning on the hot tap and how it mixes with the cold water?  Well, when you haven’t turned on the hot tap for a while, it’s going to take longer for the water to warm up. However, if you turn on the hot water in a shorter time, the water coming out will still be warm.

This is similar to what happens with your breast milk too – spacing feeds out and fuller breasts will mean there is more foremilk before the fattier hind milk is released.  If your baby is having feeds closer together, such as when they cluster feed, they will be getting more higher fat hind milk. With luck, as your little one ‘tanks up’, he might take a longer sleep after a cluster feed session.

Really, the simple rule for breastfeeding is ‘watch your baby, not the clock’.  Allow your baby to breastfeed according to his cues, whether your baby feeds frequently or whether he feeds less often but has a longer feed.  As long as your baby is feeding effectively and you are responding to his hunger signals, letting him decide when to finish at the breast and allowing him to finish the first breast before you switch sides, rather than scheduling feeds or timing ‘minutes each side’ he will be getting exactly the milk he needs.

If you are worried about your milk supply or your baby’s weight gains, please check with your lactation consultant to address this - it's more likely to be due to a feeding problem. It's not an issue of foremilk versus hindmilk.