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Breast Milk Supply 101 (And How Pumping Plays a Role)

Breast Milk Supply 101 (And How Pumping Plays a Role)

A deep dive into the basics of milk production in the early days and beyond.

The early days of breastfeeding are all about establishing your milk supply while making sure that your newborn’s nutrition needs are met.  

From the moment your baby arrives, there are a number of ways that you can begin to encourage milk production, such as doing skin-to-skin as much as possible and trying to feed on demand. Your body will catch on quickly — one of the marvels of breastfeeding is that your supply naturally adjusts to your infant’s demands. Your hormones are linked to your baby’s feeding times, hunger cues, and how much they suckle and feed.

Understanding the basics of supply, as well as how pumping can play a role, can help give you the confidence you need.

Milk Production in the Early Postpartum Days

During pregnancy, your hormones stimulate the production of colostrum. You’ll produce this thick yellow milk during your baby’s first two to four days, although some moms can even collect it in their final trimester! Because it contains important white blood cells, antibodies, and proteins, it can help build your baby’s immune system against potential infections — and is why it has earned the nickname “liquid gold.”

About three to five days after delivery, your mammary glands begin producing thinner milk that appears whiter, bluer, or grayer, though some colostrum will remain for up to six more weeks. At about two weeks postpartum, this “transitional” milk becomes “mature” milk that has all the fat and nutrients your baby needs for the first six months of their life. (This is why babies don’t need any solid food during this time!)  

When your baby cries out of hunger, your brain releases oxytocin, also known as the letdown hormone — and when they begin suckling, this oxytocin tells your milk to start flowing. As milk is removed your breast, your body is cued to produce more — replacing what your baby has just consumed. This is what people often refer to as “supply and demand.”

Because your newborn’s stomach grows from roughly the size of a cherry at birth to the size of an egg at four weeks, they can only take in so much milk at a given time. This is why they need to eat so often! A good goal is 8-12 feeds throughout a 24 period, which means about every 2-3 hours — this will help you ensure that they’re getting what they need, and give you the best chance at maintaining a healthy supply. 

Increasing Supply and How Pumping Can Help 

We’ve just walked through the period that many people call “establishing breastfeeding,” since it’s when you and baby get into a feeding routine and you allow your milk time to settle. Oftentimes, your doctor or lactation consultant may suggest that you wait to introduce a pump until you’ve reached this point – usually around the 4-6 week mark. This can help your body produce as much — and only as much — as your baby needs.

“You should only pump during these early weeks if this is the only way you can develop a breastfeeding relationship with your baby, which involves both establishing your supply and the baby’s latch,” says Dr. Laurie Jones, a pediatrician and founder of Dr. MILK (Mothers Interested in Lactation Knowledge). Shout out to the exclusive pumpers out there: we know you fall into this category!  

So what does this look like? You can try pumping directly after a nursing session for about 10-15 minutes, or until your breasts feel emptied. The goal is to remove as much milk as possible, signaling your body to produce more milk. (Note: beyond the postpartum period, this is something you can do at any point during your breastfeeding journey to boost your supply!) 

Throughout the day, you can also try “power pumping” — pumping for short periods of time in back-to-back sessions and mimicking baby’s cluster feeds. This might look like: 

  • Pumping for 20 minutes
  • Resting for 10 minutes
  • Pumping for 10 minutes
  • Resting for 10 minutes
  • Pumping for 10 final minutes 

Since this can be a lot — physically and emotionally — you’ll want to limit this to a few days. It's a temporary stopgap measure to get your supply and/or your baby's weight to a healthy, workable level, Dr. Jones says. “It’s not tenable to do this around the clock, or for long periods of time.” 


What to Know about Underproduction

There are a number of reasons, both medical and circumstantial, that you may find yourself dealing with underproduction. Maybe your baby had to spend time in the NICU (making it difficult for you to feed on demand) or had a tongue tie that impacted their ability to latch. Maybe you’ve had breast surgery or are taking medications that can inhibit production. Stress and lack of sleep can even take a toll on your supply! 

Signs that you’re dealing with undersupply include a downward trend in your baby’s growth and a clear desire from your baby for more milk. (One way a baby can communicate this is with clenched fists, instead of open hands, at the end of a feed.) 

These are real issues — but keep in mind that most moms are making enough milk for their baby, even if they don’t feel like they’re producing a lot. Plus, remember that breastfeeding is not all or nothing. Any amount you can do carries benefits for both you and your baby. And the benefits of breastfeeding increase based on its duration, so smaller amounts for longer is preferred to exclusive breastfeeding for shorter. The good news is you can get those benefits even if you don’t end up exclusively breastfeeding!


What to Know about Overproduction

Overproduction, on the other hand, occurs when your breasts produce more milk than your baby needs and can process. It’s unlikely that you’ll overproduce if you’re only breastfeeding on demand, but it can happen — you may still be learning how to interpret your baby’s hunger cues, and introducing a pump before you’ve fully established your supply can complicate things too. (But remember: it’s a myth that pumping in and of itself causes oversupply. You just need to focus on not expressing more than you need to.)

While oversupply puts you at greater risk for clogged ducts, engorgement, or mastitis, it’s totally possible to manage it by working with a lactation consultant. They’ll help you come up with a personalized plan for tapering production while helping you avoid pain and discomfort, and making sure that your baby continues to get what they need. (On the bright side, you can also build up a freezer stash!)

As with underproduction, babies can also show signs of overproduction. You might notice bowel movements that are green, frothy, or explosive, or feel baby clamping down on your breast in an effort to stop or reduce the flow.   


When you’re newly postpartum and laser-focused on nourishing your baby, it can be easy to get stressed out about your supply. 

Breastfeeding success is going to look different for every mom and baby, and any amount of breast milk that your baby receives is beneficial. While breastfeeding has proven benefits, it should never be prioritized over your own mental health. This is your permission to take the pressure off!