Understanding your breast milk supply

Reviewed by Dr. Laurie Jones

Every breastfeeding experience is a partnered dance between you and your baby. It’s one you learn together, as you navigate changing tempos and routines. And despite how practiced you become, each breastfeeding partnership is unique; if you have another baby, get ready to learn all over again!

If breastfeeding feels like an intimidating mystery at first, you’re not alone. You may be tempted to compare your experience to your mom’s, or a friend’s, or that of someone you follow on social media, but doing this can actually lead to more confusion than validation. Take whatever time you can to focus on yourself and your baby, as you begin to understand and build confidence in your supply.

One of the marvels of breastfeeding is that your breasts naturally adjust to your infant's demands. Your hormones are linked to your baby's feeding times, hunger cues, and how much they suckle and feed.

If that sounds good, but you have no idea how to do it, we’re here to help you:

  • understand the basics of milk production and breast storage capacity
  • establish a healthy supply based on your feeding goals
  • manage underproduction or overproduction
  • learn when to get help from a lactation consultant
  • look ahead to how breastfeeding evolves as your baby grows
The basics of milk production

Most breastfeeding journeys follow a fairly predictable trajectory. During pregnancy, your hormones stimulate the production of colostrum. This early thick yellow milk, which you produce during your baby’s first two to four days, helps build your baby’s immune system to fight potential infections. It packs a powerful punch, including white blood cells, antibodies, and proteins1. This is protection at its finest—it’s no coincidence that many people call colostrum 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 remains in your milk 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 months2. As you breastfeed, your body naturally produces the nutrients and quantities your baby needs.

When your baby cries out of hunger, your brain releases oxytocin, or the letdown hormone, explains Dr. Nicole M. Avena, a neuroscientist. When your baby begins suckling, this oxytocin stimulates your milk to come out and start flowing. And when breastfeeding, your baby’s suckling and removal of milk from your breast stimulates your body to produce more milk, replacing what your baby has consumed.

Because your newborn’s stomach grows from roughly the size of a cherry at birth to the size of an egg in the first month, your baby can only take in so much milk at a given time. In general, this means that when babies cry to be fed, they need to be fed—no matter the hour. And these first four to six weeks are pretty crucial; the more often you stimulate and empty your breasts of milk over a 24-hour period, the more milk you are telling your body to make.

One of the marvels of breastfeeding is that your breasts naturally adjust to your infant’s demands. This is because your hormones are linked to your baby’s feeding times and hunger cues3, along with how much your baby is suckling and feeding. Learn more about breastfeeding mechanics.

How milk production works over the long term

From the time your transitional milk comes in a few days after birth, until your baby is four to six weeks old, you’re setting your supply. Dr. Laurie Jones, a pediatrician and founder of Dr. MILK (Mothers Interested in Lactation Knowledge), advises feeding on demand during this period.

“Those first four weeks are crucial to establishing your supply,” she says. “It’s the Wild West of feeding—mayhem, on demand.”

Feeding on demand enables your baby to tell your breasts how much milk to make, thus establishing an appropriate supply. At the same time, it enables you to not worry about maintaining a tight schedule for breastfeeding or pumping sessions—let alone tracking them.


To maintain an adequate milk supply, you need to empty your breasts of milk every few hours.

When you breastfeed on demand, you’re likely to reach a steady state of supply at between four and six weeks that will stay relatively consistent until around month six. If you’re wondering how your baby can grow when your supply—and thus the calories you provide your baby—remains consistent, it’s because your baby’s caloric needs actually decline over time.

“Babies’ caloric burn actually goes down as they get bigger,” Dr. Jones says. “It’s an amazing system.”

If you’d like to support your supply, there are a few things you can do to help. These range from hydrating and maintaining additional calories in your diet, to having skin-to-skin time with your baby, to engaging in activities that reduce your stress while you feed or pump.

Checklist to help your supply

Dr. Laurie Jones


How much milk you produce is influenced by many factors, but a lot of it is biological and beyond your control. That said, a few basic ground rules can help. Get these right, and your supply should follow.

Understanding your breast storage capacity

While you can control how frequently you feed (or pump), thereby inducing your body to produce more or less milk, it’s important to note that your breasts have their own unique storage capacity. This is strictly physiological and beyond your control. It means that someone whose breasts can store more milk can go longer stretches between feeds, while someone who stores less will need to remove milk more frequently to produce that same supply.

To better describe this unique relationship, lactation consultant Nancy Mohrbacher coined the term “magic number.” It refers to the number of times your breasts need milk removed from them every 24 hours to maintain your supply (due to your breast storage capacity) and to keep your baby’s growth on track (due to the stability of milk volume and calories over time).

There is a generally recommended number of daily feeds in the first three months of your baby’s life: 8 to 12 times every 24 hours. Guidelines are guidelines, however. Your baby, and your body, are unique. After your supply reaches a steady state in the first four to six weeks, you might get a feel for a feeding tempo that works for you and the growth of your baby.

You should never stress about calculating or tracking your magic number—it isn’t even something you’ll know until after your supply reaches a steady state. Think of it as a principle that can help guide your understanding of how frequently you might need to breastfeed or pump to maintain your supply, especially if you’re going back to work, or as your baby starts sleeping longer stretches at night.

"You can't negotiate with the physiology of your breasts,” Dr. Jones says. “You may have to empty three times between 8 p.m. and 8 a.m., and other people need to empty four times. Some people need to empty zero to one time at night—and you may hate those people," she says with a laugh.

Managing underproduction

There are a variety of reasons, both medical and circumstantial, why some people either have an insufficient supply of milk or are unable to breastfeed. Being unable to breastfeed can stem from contracting an infectious disease such as HIV or tuberculosis, or galactosemia (a metabolic condition where babies can’t break down and digest milk)4.

Underproduction often results from a lack of parental leave or support, slipping below your magic number of removals each day, having multiples, or using certain medications or drugs. Breast surgeries or natural conditions resulting in insufficient or underdeveloped glandular tissue (in breasts of any size), or that affect the nerves and structure of your nipple and areola, can also impact your supply. So can a tongue tie or other physical challenge to your baby’s latch.

Signs that you are underproducing breast milk include a downward trend in your baby’s growth—or even weight loss, after the first few days of life—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.)

If you believe you have, or will have, an insufficient supply of milk, you should meet with a lactation consultant to establish a safe feeding plan and optimize your milk production to align with your personal feeding goals.

Hoping to meet certain goals even if you can’t or choose not to breastfeed?

Managing overproduction

Overproduction, on the other hand, occurs when your breasts produce more milk than your baby needs and can process. You won’t overproduce breast milk, if you only breastfeed on demand, but you may begin to overproduce, if you overstimulate your breasts—i.e., if you are pumping for your premature or low-birth-weight babies, and are having to guess their needs.

While oversupply puts you at greater risk for clogged ducts, engorgement, or mastitis, you can store and/or donate excess milk, as well as work with a lactation consultant to learn how to safely taper your supply. When you have an oversupply of breast milk, you may also experience milk leaks, sleep deprivation due to frequent milk expression needs, and even dysmorphia (where you don’t feel in control of your body).

As with underproduction, babies can also show signs of overproduction. This can include several explosive green frothy bowel movements per day, as well as your baby clamping down on the breast to stop or reduce the flow.

When to get help

Certain breast care conditions that can crop up over the course of your breastfeeding journey require immediate attention. If, for example, your breasts develop redness with one or more lumps, and you experience a fever or other flu-like symptoms, you may have developed mastitis, and you should contact your provider right away. (Check out our breast care troubleshooting guide to learn more about the most common conditions related to breastfeeding.)

A wide range of issues—some more medically urgent than others—can arise, requiring the help of professionals and specialists. Possible outcomes include getting help establishing an efficient latch, learning different breastfeeding positions, resolving engorgement, or tracking your baby’s weight gain. Learn more in our lactation support guide or schedule a virtual visit with SimpliFed to talk to a lactation consultant.

Meditation is another avenue you can explore. These 5- to 10-minute meditations have been designed to help you feel calm and centered as you breastfeed and/or pump, which can in turn improve your supply5.


Listen to these meditations

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Feeling a little lost in lactation?

Listen to this Expectful meditation (5 mins)

Feel your way through the uncertainty of your breastfeeding journey. This guided meditation encourages you to trust your instincts and extend yourself grace during moments of self-doubt.

Get the Expectful app
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Pumping while away from your baby?

Listen to this Expectful meditation (10 mins)

Pumping while you are separated from your baby can be emotionally challenging. This meditation gives you permission to acknowledge that disconnect and invite relaxation while pumping.

Get the Expectful app
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Seeking a respite during nighttime feeds?

Listen to this Expectful meditation (10 mins)

This serene meditation can assist you in appreciating those quiet, fleeting moments in the middle of the night while you’re feeding your baby.

Get the Expectful app
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Experiencing discomfort?

Listen to this Expectful meditation (10 mins)

Breastfeeding and pumping can sometimes bring discomfort. This meditation invites you to tune into your breathing and focusing on positive, affirming thoughts, as you make any necessary adjustments.

Get the Expectful app
How breastfeeding changes over time

As your baby grows, you’ll likely both get into a breastfeeding groove. Maybe your typical feeding session will go from 20 minutes to a more efficient 5 minutes. Your breasts will adjust too. They are likely to soften, even if they are producing and storing the same amount of milk.

As your baby’s mouth grows, the latch will also naturally become more comfortable and efficient. And as you and your baby get to know each other better, you will establish favorite feeding positions and rituals.

When and how you stop breastfeeding can be a very personal and intentional choice, or it can feel entirely out of your control. Do your best to enjoy the breastfeeding experience for however long it lasts. Focus on the bond you’re establishing, the nutrients and protection you’re providing, and the magic of what your body can do.


1 https://my.clevelandclinic.org/health/body/22434-colostrum

2 https://wicbreastfeeding.fns.usda.gov/phases-breast-milk

3 https://www.ncbi.nlm.nih.gov/books/NBK148970/

4 https://publications.aap.org/pediatrics/article-abstract/67/2/300/50053/When-Should-One-Discourage-Breast-feeding

5 https://pubmed.ncbi.nlm.nih.gov/35240703/

Additional resources

The mechanics of breastfeeding

Knowing how your and your baby's bodies innately work together can provide foundational guide posts as you find your rhythm.

Sleep and milk production: How they’re linked

The number of feeds you do at night impacts your supply (and by extension, your sleep), but it’s complicated.

Where to go for lactation support

Even the smoothest breastfeeding journeys can have a few bumps in the road. Here's more information about the support available.