How to Store and Freeze Breast Milk

How Long Does Pumped Breast Milk Last?

Whether you are storing breast milk at room temperature, refrigerated, or frozen, it has a limited lifespan and should be used before losing nutrients or turning sour.

In order for breast milk to provide the most nourishment possible for healthy growth and development, it needs to be used within a certain timeframe. That period can vary greatly depending on your method of storage!

How to Store Your Breast Milk

That’s why it’s always important to:

  1. Label your breast milk with the date and time it was pumped to keep track of what’s fresh.
  2. Frequently clean out the fridge and freezer to discard spoiled milk.
  3. Utilize the sniff test and discard any milk that smells sour, even if it hasn’t met its expiration date.

Breast Milk Lifespan

The lifespan of freshly expressed breast milk varies from one storage method to another because of the relationship between temperature, exposure, and bacterial growth. Some recent studies show fresh breast milk has higher caloric and lipid content when compared to frozen milk. So if possible, after using your breast pump, use the milk as soon as you can. If you intend to store your breast milk, seal it tightly and place it in the refrigerator or freezer as soon as possible. Also, remember to wash your hands and sterilize your equipment before pumping!

  • How long does fresh breast milk last?
    Freshly pumped breast milk can be stored at room temperature for 4 to 6 hours. It’s best to use it within four hours. It should always be covered and kept as cool as possible, between 66 to 78F. Do not freeze fresh milk after it’s been left at room temperature for more than 2 hours.
  • How long does breast milk last in a cooler?
    After expressing milk, you can store it in a cooler or insulated cooler bag with ice packs for about 24 hours. How cold your cooler is will determine if it will be safe to freeze your milk. Freeze it within 24 hours of chilling it, but only if it passes the sniff test.
  • How long does breast milk last in the refrigerator?

    You can store your milk in the fridge for up to five days at 32° to 39°F. Be sure to place your milk in the back of the refrigerator, away from the door or items that could knock it over.

    As long as breast milk still smells fine, it can be frozen after spending up to 48 hours in the fridge.

  • How long does breast milk last in the freezer?
    You can store breast milk in the freezer for up to 6 months. It will last up to 12 months in the back of a deep freezer, but using frozen milk within 6 months is best.

Be sure to freeze breast milk in storage bags that are specifically intended for freezing and that are BPA-free. They often come pre-sterilized and cannot be reused.

Liquids expand as they freeze, so leave a little space at the top.

Place your breast milk in the back of the freezer, where the temperature will be the most consistent. Avoid placing it near the door, where your breast milk could start to thaw when it’s opened.

Thawed breast milk should be discarded after use. Do not place it in the fridge or refreeze it.

How Do I Thaw Frozen Breast Milk?

There are two different ways to safely thaw frozen breast milk.

  1. Remove it from the freezer and place it in the fridge. Thawing frozen milk completely takes about 12 hours. It’s recommended to place it in the fridge the night before you plan to use it.
  2. Hold the breast milk collection container under lukewarm running water to evenly warm it up. Never thaw breast milk by microwaving it. It could cause uneven hot spots that burn your infant and destroy some of the nutrients.

    • Swirl the milk with your finger to ensure the temperature is consistent and to mix the creamier layer on top with the watery layer on the bottom.
    • Serve the milk to your infant within two hours after it’s brought to room temperature or heated.
    • Discard thawed milk after it’s been in the refrigerator for 24 hours.
    • Milk that has been frozen may have a higher fat content that gives it a soapy smell. Do not be alarmed, it does not mean it’s spoiled.

How Do I Warm Up Breast Milk?

There are a few different ways to properly heat breast milk.

  1. See what your baby likes; after they are a few months old, they may prefer chilled milk from the refrigerator.
  2. Place your milk container in a bowl of warm water to evenly warm it up. Test the temperature before feeding your baby to avoid burning their mouth or throat.
  3. Use a bottle warmer to safely warm your breast milk.
    • Never heat breast milk on the stove, in boiling water, or in the microwave. Breast milk heated above 104°F significantly impacts the nutritional and immunological properties of milk.
    • Swirl it around with your finger to make sure the temperature is evenly distributed and to mix the different layers. Do not shake.
    • After refrigerated breast milk has been warmed to room temperature, discard it after two hours. Do not place leftover milk back in the fridge.

Click here for more information on breast milk storage guidelines from the CDC.

Should I Use a Bottle or Breast Milk Storage Bag?

The right containers are crucial for proper breast milk storage. Breastfeeding moms can safely store their milk in glass, hard plastic bottles, or BPA-free milk storage bags. Avoid using disposable bottles or regular bags found around the home. Your storage container needs to be specifically for breast milk.

If you would like to use bottles:

  • Use glass or hard plastic storage bottles that are BPA-free
  • Make sure they’re leak-proof
  • Breast milk storage bags are another great option, especially for freezing human milk

How Much Breast Milk Should I Store?

It can be beneficial to store breast milk in smaller amounts, such as 1 or 2 ounces so that it will thaw faster. This will help to avoid overfeeding your baby or wasting milk. However, pay attention to your infant’s individual needs over time. At 1-2 weeks old, babies need 2-3 ounces. This amount increases to 3-5 ounces between 1 and 6 months of age.


About the Author

Jessica Madden, MD, is the Medical Director at Aeroflow BreastpumpsDr. Madden has been a board-certified pediatrician and neonatologist for over 15 years. She's currently on staff in the neonatal intensive care unit (NICU) at Rainbow Babies and Children’s Hospital in Cleveland, OH. She previously worked in the Boston and Cleveland Clinic Children’s Hospitals. In 2018 she started Primrose Newborn Care to provide in-home newborn medicine and lactation support. She also enjoys traveling, yoga, reading, and spending time with her children.

Information provided in blogs should not be used as a substitute for medical care or consultation.

Share: