Who transfers the milk?

The video below is of a baby born at 35 weeks gestation (see a larger and longer version of the video), now 5 weeks old. The mother is breastfeeding and supplementing with a bottle. The video shows that the widely held notion that breastfeeding “tires out the baby” is false. Babies respond to milk flow. In this video, when the milk flow slowed, the baby started to fall asleep and the video starts with the baby essentially asleep and not sucking. When the flow is increased by supplementation with a lactation aid at the breast, the baby wakes up, opens his eyes and sucks vigorously. The video illustrates two related realities:

Which realities?

1. That young babies respond to milk flow and tend to fall asleep when the flow slows (Watch older babies may pull away from the breast when the flow slows) and

2. Babies don’t “transfer” milk, mothers transfer milk. The baby, of course, does his part, which is to stimulate the breast so that the milk flows from the breast to the baby.  This is why a good latch helps the baby get more milk.  When the baby latches on poorly, the breast is not stimulated well, and milk does not flow well from the breast. But the baby doesn’t “suck the milk out of the breast”.

This baby was not receiving milk well from the breast.  To increase the amount of milk he receives, the mother was shown how to latch the baby on with an asymmetric latch. An improved latch and breast compressions resulted in the baby receiving significant amounts of milk.

The above becomes obvious, I think, when we imagine a baby waking up from a sleep and perhaps starting to cry. Many mothers would have a milk ejection reflex (letdown reflex) and the front of their blouse would become wet. So, who transfers milk? Obviously, it’s the mother. It is necessary to emphasize that the baby does his part, letting the mother know he’s hungry, but it’s the mother who transfers the milk.

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What are some of the implications?

1. Breastfeeding is not tiring for the baby. Babies respond to milk flow.  If the flow of milk is slow, the young baby tends to fall asleep, as in the video.  The older baby may pull away from the breast, or fuss at the breast. If we increase the flow of milk, the “tired” baby suddenly is wide awake and sucks vigorously.

2. Babies (whether full term, babies with cardiac problemspremature babiesdo not use up more energy breastfeeding than they do bottle feeding. This seems to be almost universal thinking at cardiology units and intensive care units in pediatric hospitals around the world.  As a result of such thinking, mothers are told that they cannot breastfeed their babies because the baby will tire out from the breastfeeding and we need to conserve his energy.  This is thought to be true even of healthy, full term babies.

3.  It is not easier for the baby to feed from a bottle than from the breast. Too often pediatricians, neonatologists, and pediatric cardiologists, tell mothers not to breastfeed because it takes too much work for the baby to breastfeed and it’s better to bottle feed.

4. Babies do not need “strong” muscles in their cheeks to breastfeed. This is said to be one of the reasons that “near term” babies have difficulties breastfeeding.  It is not true that “near term” necessarily have difficulties breastfeeding.  Babies much more immature than 36 or 35 weeks gestation can latch on and breastfeed just fine.  What changes for “the worse” when the baby is born at 36 or 37 weeks, for example?

5. Babies are not “lazy”. They respond to milk flow.  And it follows that normal babies do not have “weak sucks”, unless they are affected by medication or some other cause of depression of the nervous system.  If the flow of milk from the breast is steady and rapid, the baby will suck just right and not fall asleep if he is latched on well.

6. We teach a technique we call “breast compression” to increase the transfer of milk from the mother to the baby. It works very well much of the time. The technique helps the mother transfer more milk to the baby.  If mothers use breast compression to increase of flow of milk to the baby, they understand that, of course, mothers transfer milk not babies.

7. “The more the baby sucks, the more milk the mother will make“. This is simply not true.  The mother does not make more milk simply because the baby is sucking for a long time.  A baby “nibbling” on the breast is not receiving milk and not stimulating more milk production.

We think about babies and pumps working in the same way, and thus, the baby should keep sucking milk out of the breast, like a pump. Except that it is the mother who transfers the milk, not the baby.  And even pumps do not get milk indefinitely.

And the result of this mistaken idea?  Mothers keep babies on the breast for long periods of time thinking this will increase their milk supply.  But a “nibbling baby: does not increase the milk supply because babies do not transfer milk.

And when mothers need to supplement, using a lactation aid at the breast, they do not introduce the lactation aid early enough.  Many will wait much too long, when the baby has stopped drinking and is sitting on the breast nibbling away, not receiving milk.  Thus, the baby is on the breast for long periods of time, and the lactation aid is blamed not only for the length of the feedings, but also that the lactation aid results in the mother producing less milk. Which is a strange notion.  If anything, using the lactation aid at the breast increases the milk supply.


This baby is hardly getting milk from the breast.  He is nibbling only.  He could sit nibbling on the breast for hours and still the mother’s milk supply will not increase. 

8. And why would breast compression help? Mothers transfer milk, not babies. Because the baby isn’t doing his part as well as he could and so breast compression compensates for his not doing his part as well as he could. And the reason? The baby is not as well latched on as well as he could be. And why is the baby not latched on as well as he could be?

a. The way the baby is latched on. See also latch quiz.

b. Use of artificial nipples such as bottles and nipple shields and and pacifiers and

c. The baby has a tongue tie. Recently we saw a baby of 3 days of age with a very tight tongue tie. Before the release of his tongue tie, the baby was receiving almost no milk from the breast. After the release of the tongue tie, the increase in the amount of milk the baby received from the breast was dramatic. It is obvious that the milk supply and flow of milk to the baby did not increase dramatically in the 15 between the first feeding before the tongue tie was released and the second feeding after the tongue tie release.  What changed was how the baby latched on and the mother’s response to the “new” latch. For this reason, tongue ties should be released early, before the mother’s milk supply reduces. How I wish we had filmed this baby.

d. A decrease in the mother’s milk production itself, can also result in a poor latch. How? Because when milk supply and flow of milk to the baby decrease, the baby tends to slip down on the breast to the nipple.  If the baby is latched on only on the nipple, the milk flow to the baby decreases even more.  And the mother may start to have late onset sore nipples.

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Copyright: Jack Newman, MD, FRCPC, Andrea Polokova, 2017, 2018, 2020