Frequently Asked Questions about Milk Production

By Kelly Bonyata, BS, IBCLC

How does milk production change over the course of lactation?

For the first few days, up to and including the point at which mom’s milk “comes in,” milk production does not depend upon milk being removed from the breast. After those first few days, it is necessary for milk to be regularly removed from the breast (via baby or pump) to continue milk production. The breasts will begin to shut down milk production within several days if milk is not regularly and effectively removed.

During the early weeks, assuming nursing is going well, a mom will often have more milk than baby needs. Many moms also experience varying degrees of leaking and/or breast fullness/engorgement in the early weeks — this is not the norm for the entire breastfeeding experience but simply a period of adjustment as mom’s body determines and adjusts to the amount of milk her baby (or babies) actually needs.

In exclusively breastfed babies, milk intake increases quickly during the first few weeks of life, then stays about the same between one and six months (though it likely increases short term during growth spurts). Current breastfeeding research does not indicate that breastmilk intake changes with baby’s age or weight between one and six months. Sometime between six months and a year (as solids are introduced and slowly increased) baby’s milk intake may begin to decrease, but breastmilk should provide the majority of baby’s nutrition through the first year.

After the first 6 weeks to 3 months (or sometimes later – this varies for different mothers), the high baseline prolactin level that is the norm in the early weeks gradually decreases to the lower baseline that is the norm for later lactation. Around this time, mom’s breasts may feel less full, leaking may decrease or stop, let-down may become less noticeable, and pumping output may decrease. These are all normal changes and, on their own, do not mean that milk supply has decreased. Click here to read more…

I’m confused about foremilk and hindmilk – how does this work?

The breast only makes one type of milk, which has a relatively high fat content, but because of the mechanics of milk release, the amount of fat in the milk available to baby gradually changes as a feed progresses. Foremilk is the term for the milk (relatively lower in fat) available at the beginning of a feeding; hindmilk is the term for the milk at the end of a feeding, which has a higher fat content than the milk at the beginning of that particular feeding. There is no sharp distinction between foremilk and hindmilk – the change is very gradual. Research from Peter Hartmann’s group tells us that fat content of the milk is primarily determined by the emptiness of the breast — the less milk in the breast, the higher the fat content. Click here to read more…

What happens between feedings?

Milk is produced at all times, not just between feedings. Between feedings, milk collects in mom’s breasts. Volume of milk stored in the breast is greater when there has been a greater amount of time between feeds. The amount of milk that can be stored in the breast between feedings (milk storage capacity) varies significantly from mom to mom and is not determined by breast size (although breast size can limit storage capacity). For most women there is not a lot of storage room. Although mothers with both low and high milk storage capacities produce enough milk for their babies, mothers with a greater milk storage capacity may be able to go longer between feedings without impacting milk supply and baby’s growth.

Do breasts need time to refill?

Many people mistakenly think of a mother’s milk supply as being like “flesh-covered bottles” that are completely emptied and then need time to refill before baby nurses again. This is simply not how we understand milk production to function.

First of all, milk is being produced at all times, so the breast is never empty. Research has shown that babies do not take all the milk available from the breast – the amount that baby drinks depends upon his appetite. The amount of milk removed from the breast varies from feed to feed, but averages around 75-80% of the available milk.

! Trying to completely empty a breast is like trying to empty a river — it’s impossible, since more milk will keep flowing in while milk is being removed.

Research also tells us that the emptier the breast, the faster the breast makes milk. So when baby removes a large percentage of milk from the breast, milk production will speed up in response.

! Rather than thinking of nursing or pumping as “pouring milk out of a container” think of it as flipping on the “high speed production” switch!
! Yet another analogy: Imagine you are using a straw to drink from a glass of water. As you drink, a friend is very slowly pouring water into your glass. The emptier the glass, the faster your friend pours the water. Would you be able to drink all the water in your glass?

Waiting a set amount of time to nurse your baby (under the mistaken belief that breasts need time to “refill”) is actually counterproductive. Consistently delaying nursing will lead to decreased milk supply over time because milk production slows when milk accumulates in the breast.

Return to How does milk production work?

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