Foremilk and hindmilk

Foremilk and hindmilk are not two distinct types of milk but rather descriptive terms for the way fat content changes during a breastfeed. La Leche League GB explains that "'foremilk' is defined as the milk available initially when a baby starts feeding, 'hindmilk' as the milk that can be expressed at the end of a feed."

Why does fat content change during a feed?

According to La Leche League GB, "fat content increases gradually as the breast becomes emptier, as fat globules are 'forced' out of the breast by successive milk ejections." When the breast has been full for longer between feeds, fat adheres to the breast tissue, meaning the initial milk of the next feed may be lower in fat. Conversely, when feeds are frequent, the milk at the start of a feed tends to be higher in fat.

Is foremilk always low in fat?

La Leche League GB cautions against this common misconception: "'foremilk' is not necessarily 'low' in fat, as it depends on how much time has passed since the previous feed." The organisation also notes that feed duration is not a reliable indicator of fat content: "you can't tell anything about fat content from the length of the feed" — some babies take a full feed in four minutes while others take forty minutes.

Does a baby need to stay on one breast to get enough hindmilk?

La Leche League GB advises that deliberately limiting a baby to one breast to ensure hindmilk may reduce milk supply by leaving the other breast unused for longer. Restricting to one breast is described as appropriate only in cases of genuine oversupply where rapid weight gain and signs of overactive let-down are present. The guidance supports allowing the baby unrestricted access and switching breasts when the baby comes off or the breast feels soft.