Has someone suggested to you that your baby isn't gaining weight as expected and the solution is to get baby to ingest more hindmilk? It has become common knowledge that fat content of milk changes throughout breastfeeding. This is true. Milk doesn't change in each feeding session in the same way...it changes over the course of the day and feeding patterns. The anxiety about whether or not baby is feeding "long enough" to get to the hind milk is not necessary.
Something else that is true is that the longer a baby feeds, the more letdowns occur and more fat is released into the milk from the milk making glands, however...there are some things that need to be pointed out and kept in mind.
Foremilk and hindmilk are not two different kinds of milk. Women do not produce a low fat milk and a high fat milk. It is simply that the first milk a baby receives at the start of a feed is foremilk and the milk after that is hindmilk. The change is gradual It is not based on a percertange of fat content, like skim, 1%, 2% or whole milk that we are used to thinking of. There is no magic time in a feed that changes the fat content or we can see a switch of kind of milk. There is no percentage of fat a baby needs to be able to gain wright. On this note, all the foremilk is not always lower fat than all the hindmilk. Foremilk from one feed might have a higher fat content than hindmilk from the next feed, previous feed or other feeds in the day.
With this all in mind, when there is a weight gain concern, the focus needs to be on increasing intake of milk and looking at the factors that might be impacting intake & not trying to avoid foremilk. Strategies to avoid formal and increase hindmilk consumption are ideas like pumping foremilk before a nursing session, so baby can only access hindmilk or keeping baby on one breast for 15 or 20 or 40 minutes, depending on who is giving the instructions. In fact, sometimes these strategies means the baby is getting even less milk than before. It is the total daily milk intake that determines successful weight gain. We cannot look at one feed as the way it is for all feeds. We need to look at each day and all the breastfeeding sessions combined and then address ways to increase milk intake overall.
If you find yourself in the situation of having an infant that is not gaining as expected, not gaining at all, slowly gaining or losing weight, I suggest a full evaluation with an IBCLC.