You’ve just come back from a checkup on your baby, and weight gain has been a little lower than you would like. The advice given was to keep the baby on one breast at each feed to make sure that they access the “hindmilk” and to only feed every 3 hours to make sure your breasts have time to'refill' between feeds. You do this for the next two weeks, only to discover that weight gain has fallen even further behind. What’s going on?

What are foremilk and hindmilk?

First of all, this is a concept that the vast majority of mums will never have to give any active thought to at all, but this is an explanation of what we mean by these terms for reassurance. During a feed, the available fat in the milk changes slightly. Fat globules within the milk will'stick' to each other and to the alveoli (where milk is made). Between feeds, your body continues to produce and store milk. This milk collects in the breasts, moving forward towards the nipple. This initially available milk will have slightly fewer fat globules than milk taken in towards the end of the feed. The longer the gap between feeds, the more this is so.

What can be confusing is that foremilk and hindmilk are not separate or different types of milk, and there is no'switch over’ point where foremilk becomes hindmilk, but rather a gradual change of fat within this individual feed. Not every feed will even have distinguishable differences between the start and end of the feed; this is because the emptier the breast, the higher the fat content in the milk (and so a woman who feeds frequently will have more fat in the initial let-down than a woman who hasn’t fed for several hours).

Our general rule of thumb for feeding a baby is this: let the baby stay on one breast for as long as they are mostly actively drinking. Then offer them a turn at the second breast. If necessary, after they are no longer actively drinking from the second breast, you can re-offer the first breast. Some women will find that they rarely need to offer more than one side per feeding, while others will routinely offer three or even four sides in each feed.

So why isn’t my baby gaining weight?

In most cases, the simple reason why a baby isn’t gaining enough weight is that they aren’t drinking enough milk! In our example above, the mother was advised to stay on one breast per feed; however, her baby gained even less than previously. This is due to her now only offering half (or even less) of the available milk at a feed by mistakenly not offering both breasts.

The advice to stay on one breast for longer can be very dangerous; beyond a certain point, a baby with faltering weight gain will likely no longer be transferring much milk (think those shallow, intermittent sucks as compared with the slow, deep, purposeful sucks at the beginning of a feed). Leaving a baby for an additional 20 minutes on the first breast may get them a few mouthfuls of extra ‘fatty’ milk. However, moving that baby to the other breast will result in a fresh burst of deep, purposeful sucking, with significantly more milk transfer. In fact, the actual correct advice for faltering-growth babies would be to switch breasts whenever they are no longer doing the good ‘drinking sucks'—a baby may do several sides within a feed rather than just one side, which will result in significantly more milk transfer and therefore better weight gain. As an added bonus, this frequent switching of sides also increases the overall milk supply.

In addition, restricting feeds to a schedule denies them additional feeding opportunities that they may need in order to gain weight.

Is my milk of good enough quality?

Maternal diet does not affect the composition of the macronutrients in milk (protein, lactose, and fat). These macronutrients are the drivers of weight gain and are roughly similar in all lactating women. This means that babies drinking a similar volume of milk from different mothers will all get approximately the same calories from this milk. Calories (milk intake) drive weight gain, and therefore, if your baby isn’t gaining as much as we would like, the issue is not the quality of your milk but rather the quantity that they are drinking.

Should I leave longer gaps between feeds for my breasts to refill?

The emptier your breasts are, the faster your body makes more milk. Imagine your breasts as a combination of a river and a lake. The lake is the'stored milk'—the v volume that can be stored in your lake is individual to each woman, but often a woman who’s baby is struggling with weight gain has a small lake. However, there is also a river, and this will continue to flow while the baby is drinking.

The trick to additional weight gain is often to add in an extra feed or two in the day to give babies more opportunities to drink from the ‘river’.

What is foremilk and hindmilk?

For our Baby Feeding Journey, Unii Expert Wendy Lever demystefies foremilk and hindmilk.