Collecting & Storing Breast Milk

November 29, 2011

Storing breast milk is a great option no matter if you’re returning to work, exclusively pumping, or just looking to give other family members an opportunity to feed your little one. The benefits of breastfeeding are extensive, however it’s important that nursing mothers understand breast milk storage guidelines and safe handling instructions before they get started. So, use the information below as reference when giving your baby the best nutrition possible.

Breast Milk Storage Guidelines:

  • Room Temperature: 4 to 6 hours
  • Cooler with 3 Ice Packs: 24 hours
  • Medela Cooler Bag with Ice Pack: 12 hours
  • Refrigerator: 3 to 8 days
  • Deep Upright Freezer: 6 to 12 months
  • Freezer Compartment of Refrigerator (separate doors): 3 to 6 months
  • Freezer Compartment of Refrigerator (one door): 2 weeks
  • Thawed Breast Milk: 24 hours (Do not refreeze)

Safe Handling Instructions for Collecting and Storing Breast Milk:

  • Store breast milk in clean, BPA-free containers intended for breast milk storage.
  • It is normal for stored milk separates into layers with the cream at the top.  Gently swirl warmed bottles to mix the milk layers. Don’t shake.
  • You can continue to add small amounts of cooled breast milk to the same refrigerated container throughout the day.  Avoid adding warm milk to already cooled milk.
  • Pumped milk may be added to frozen milk provided it is first chilled and the quantity is less than what is frozen.
  • Store your milk in collection bottles or in disposable bags specifically designed for breast milk. Avoid using plastic bottle inserts.
  • Freeze milk in 2 to 5 ounce portions.  Small amounts will thaw more quickly.  You will also waste less milk this way and avoid over-feeding.  Liquids expand when frozen so be sure to leave some extra room at the top of the container so the bottle or bag won’t burst.
  • Seal containers tightly.  Write the date on a piece of tape on the bag or bottle.  You can also use Medela’s Labeling Lids for convenient organization.
  • Sometimes defrosted breast milk can have a soapy taste or odor.  This is due to a normally occurring enzyme, lipase, which helps to digest the fat content of the breast milk.  To avoid this from occurring, scald the breast milk (do not bring to a boil) on a stove until tiny bubbles appear along the sides of the pan; do this before it is frozen.  The scalding process will neutralize the enzyme preventing the soapy taste or smell.
  • Never microwave breast milk.  It causes hot spots that can burn your little one’s mouth.  Microwaving can also change the composition of breast milk.
  • Thaw milk overnight in the refrigerator, or hold the bottle under warm running water to quickly thaw.  You can also place the sealed container in a bowl of warm water for 20 minutes to bring it to body temperature.

Note: These guidelines may differ if your baby was born premature. Check with your healthcare provider for specific breast milk guidelines for premature babies.

Looking for a breast milk storage guidelines quick reference? You can download the chart below by clicking here.












Do you have any tips for breast milk collection and storage? Share them in the comments below.

97 thoughts on “Collecting & Storing Breast Milk

  1. Is it safe to move refrigerated breast milk to a cooler for traveling about 2 hours away? Or is it safer just to move my refrigerated breast milk to the freezer if it’s been pumped a day before? How long is expressed breast milk good for in a refrigerator? I keep getting different answers and I just don’t want what we have pumped to go to waste for a few days that we are gone.

    • Hi Vanda – Your refrigerated milk will be okay in a cooler for up to 24 hours. You can store your milk in a refrigerator for 3 to 8 days. We hope this helps!

  2. Is the following sequence a valid option:

    (1) Express milk and store in Medela Cooler + 1 ice-pack for up to 5-6 hours.
    (2) Later the same day, store same milk in hotel refrigerator for up to 24 hours.
    (3) The day after, put the milk back in the Medela Cooler + 1 ice-pack for up to 7-8 hours.
    (Note) Some newly expressed milk may be added during the above intervals (1), (2), and/or (3).

  3. Can you mix different stored bags of breast milk together? Example… I pumped 2 oz and put it in the fridge, the next day I pumped 4 oz and put it in the fridge. My baby eats 3 oz at a time. Can I mix the 2 oz and the remaining 1oz together in a bottle for her?
    Thank you!

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