How to Store Breast Milk: All About Proper Storage

If you’re breastfeeding, there are many reasons you might want to store your breast milk. For example, you might want to pump or express while you’re at work to and store your milk to give to your baby later, or there may be times when you want to put aside a few bottles of breast milk so that someone else can feed your little one later.

Read on to learn how to collect and safely store breast milk, and how to defrost and reheat breast milk that has been kept in storage.

How to Collect and Store Breast Milk

Whether you have a larger supply of breast milk and want to put some aside for later use, or if you need to go back to work while still breastfeeding and need to delegate some of the feeding duties to your partner or a babysitter, you might need to collect breast milk for storage.

Types of Breast Milk Storage Containers

Portioning the Breast Milk for Storage

Hygiene Guidelines for Pumping Breast Milk

Types of Breast Milk Storage Containers

The following are options for storing breast milk, and the recommended containers to use:

  • It’s best to collect freshly pumped or expressed breast milk in clean glass or plastic screw cap bottles or hard plastic storage cups with tight-fitting lids.
  • Avoid any plastic containers that have the recycling number 7, as this means the container may have been made with BPA-containing plastic.
  • You can also use special breast milk storage bags that are pre-sterilized for storing breast milk.
  • Don’t store breast milk in disposable bottle liners or regular plastic storage bags that weren’t designed for breast milk storage.

Some baby bottles are designed so you can store breast milk in them straight after pumping. Read up on baby bottles for more info on them.

Portioning the Breast Milk for Storage

Store the breast milk in two- to four-ounce portions, which is about the right amount for one feeding (read more on breastfeeding), in order to avoid waste.

Mark whichever storage container you’ve chosen with the date of pumping, and with your baby's name if the milk will be consumed at day care. Always use the oldest stored breast milk first, as long as it’s still within its use-by limit.

If you’re going to place the container in the freezer for storage, make sure to leave an inch of air space at the top since the liquid will expand when frozen.

Hygiene Guidelines for Pumping Breast Milk

There are some steps you can take to prevent transmitting bacteria to the breast milk and to your baby.

Before using your breast pump for the first time, make sure to sterilize all its parts, including the nipples, bottles, and any parts that come into contact with your breasts or the milk.

Sterilize by boiling the parts for 5 to 10 minutes. Check the manufacturer’s directions for sterilizing and follow the recommended boiling time in case it’s a little different.

Each time you use the pump, make sure to wash your hands thoroughly.

After every time you use the pump, make sure to wash the parts in hot, soapy water, or in the dishwasher, if the parts are dishwasher safe.

Time Guidelines for Breast Milk Storage

Freshly expressed or pumped breast milk can be stored in several ways. Whether you’d like to know how long you can store your breast milk for in the fridge or freezer, here are the maximum times it can safely be stored for:

Fresh Breast Milk Storage Times

Storage spot

Storage time

At room temperature of about 77 degrees Fahrenheit

Up to 4 hours


Up to 24 hours

Refrigerator set to below 39 degrees Fahrenheit

Up to 3 days

Freezer set to 0 degrees Fahrenheit or below

Up to 6 months

Deep freezer set to -4 degrees Fahrenheit

Up to 12 months

If the breast milk is left over from a previous feed it must not be stored and should be used within 2 hours, or discarded.

Thawed breast milk can be kept at room temperature for 1 to 2 hours before use, or kept in the fridge for up to 24 hours before use. Thawed breast milk must never be refrozen!

How to Defrost Frozen Breast Milk

Follow these tips for thawing breast milk stored in the freezer:

  • Thaw frozen milk by holding the container under cool running water. As it begins to thaw, switch to warm running water.
  • Or allow the frozen breast milk to thaw in the fridge — it might take about 24 hours.
  • Once the milk has thawed, give it to your baby within 24 hours.
  • Never thaw frozen milk at room temperature.
  • Do not refreeze thawed breast milk.

Can You Reheat Chilled Breast Milk?

Yes. Breast milk that’s been stored in the refrigerator, whether it’s been previously frozen or not, can be reheated if you would like to give your baby warm milk. But know that breast milk does not need to be given to your baby warm. It’s OK to feed your baby breast milk that’s chilled or at room temperature.

If you wish to reheat breast milk after storage in the fridge, follow these steps:

  • Place the bottle of breast milk in warm water. Use a pan or bowl of warm water to reheat your baby’s bottle, or use a bottle warmer.
  • Do not heat bottles on the stovetop or in the microwave. High temperatures can kill breast milk’s disease-fighting antibodies and can also create hot spots that could burn your baby’s mouth.
  • Check that the milk’s not too hot. Before feeding your baby, test the temperature of the breast milk by squirting it on the inside of your wrist to ensure it’s not too hot for your baby. It should feel warm on your wrist.
  • Don’t wait too long to give the breast milk. Once you’ve warmed the breast milk, it should be used within two hours.

Is Stored Breast Milk Any Different From Fresh Breast Milk?

Breast milk that’s been in storage, either in the refrigerator or thawed from the freezer, can look different from freshly expressed or pumped breast milk. It may even separate into a creamy layer and a milky layer. This is completely normal. Gently swirl the milk to mix it back together.

Thawed frozen milk may also smell or taste different due to a breakdown in the milk fats. It’s still safe for your baby, and most babies won’t notice the difference.

You can try mixing the previously chilled breast milk from storage with fresh breast milk in a 1:1 ratio. It’s best that the two milks are close in temperature when you do this.

If your baby does not finish the bottle of stored milk, the leftover breast milk can still be used within two hours. After that it should be discarded.


  • How long can you keep breast milk out of the fridge?

If you’ve removed breast milk from the refrigerator after a period of storage, once it reaches room temperature, it can be kept at up to 77 degrees F for up to 4 hours.

  • How long does breast milk last after warming?

Once you’ve warmed breast milk or brought it to room temperature, it should be given to your baby within two hours.

  • How much breast milk should I store?

You can store as much breast milk as you would like, but it’s a good idea to store breast milk in storage containers that hold two- to four-ounce portions (about the amount that will be offered to your baby at one feeding) to avoid waste.

  • How long is breast milk good at room temperature?

You can store breast milk at room temperature for up to 4 hours at no warmer than 77 degrees F.

  • How long is breast milk good in the fridge?

In the fridge (set to 39 degrees F or below), you can store breast milk for up to 3 days. Make sure not to store the milk in the door, as that area may fluctuate in temperature when you open the fridge.

  • How do you store breast milk in the freezer?

Breast milk can be frozen (with your freezer set to 0 degrees F or below) for up to 6 months, preferably in the back of the freezer. It can be stored in a deep freezer set to -4 degrees for up to 12 months.

  • How long does breast milk last in a cooler bag?

If you’re planning on taking a short trip or need to transport breast milk to a caregiver, it can be kept in a cooler with frozen ice packs for up to 24 hours. Once out of the cooler bag, the breast milk should be given to your baby as soon as possible, or placed in the refrigerator or freezer right away.

The Bottom Line

For busy moms like you, expressing or pumping breastmilk and then storing it can be a lifesaver. Having breast milk in storage can make it easier to keep up with your baby’s feedings and allow you to share feeding duties with others. Using the info in this article and by giving it a try, you’ll soon get the hang of storing, thawing, and reheating breast milk and it will become a natural part of your life with your little one.

After all those feedings, you’ll be doing a lot of diaper changes! To earn points for all those diaper purchases, download the Pampers Rewards app today.


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