Differentiating Milk Transfer During Breastfeeding

Milk transfer is the movement of milk from the lactating parent's breast/chest, out through the nipple, and into the baby's mouth where it can be swallowed. But have you ever stopped to think about differentiating who actually performs milk transfer during breastfeeding/chest feeding- the baby, the lactating parent, or both? This is an important concept to understand, as it will help to determine the effectiveness of the feeding session.

The very first breast/chest feeding, if done within an hour or two of the baby's birth, will likely involve the baby doing the milk transfer. Colostrum is readily available, and most babies are able to suckle and receive this milk that is already primed throughout the breast/chest and nipple.

But then milk transfer becomes murky.

Milk production now depends on the amount of lactational hormones- mainly prolactin and oxytocin. The lactating parent is responsible at this point to increase these hormones, by frequent milk removal and lots of skin-to-skin time with the baby. Obviously, without milk production, minimal milk transfer can occur. Until the parent is able to guide their baby to latch well and suckle fairly vigorously, milk transfer will be minimal and will rely on let-downs (milk ejections) and breast/chest compressions from the lactating parent.

As milk production increases and the baby gets more skilled at latching and suckling, milk transfer is shared between the lactating parent and the baby. A well-latched baby's tongue compresses the breast/chest, sending milk from the alveoli (milk-making sacs) through the milk ducts, out to the pores on the end of the nipple. Immediately after swallowing, the baby's tongue drops creating a vacuum (negative pressure) which causes more milk to move through the breast/chest. The amount of contribution the baby makes can change over the course of the day, so parents need to pay attention and should be performing breast/chest compressions throughout the feedings as needed.

As the baby matures and milk production increases, the lactating parent contributes to milk transfer by having a robust amount of milk and when having let-downs, but the baby does most of the milk transfer.

A baby who is latched onto the nipple, instead of the breast/chest, will not contribute much to milk transfer, as they will be closing off the milk ducts to milk flow and will not be contributing to moving milk out of the alveoli. Using a nipple shield decreases the amount of negative pressure applied to the nipple tip, thereby reducing milk flow through the breast/chest. A preterm, late preterm, or even an early term baby likely will not create enough vacuum pressure to create milk flow. All of these scenarios will rely on the lactating parent to perform breast/chest compressions and perhaps use breast/chest feeding tools with or without supplementation to ensure adequate milk transfer until the baby is able to latch well and suckle vigorously. Anytime the baby is ill, the lactating parent might have to revert back to doing more to contribute to milk transfer as well.

So now that you know that you know that milk transfer is dynamic, are you better prepared to assess feedings?