Collecting & Storing Breastmilk

November 29, 2011

Storing breastmilk 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 breastmilk 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.

Breastmilk 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 Breastmilk: 24 hours (Do not refreeze)

Safe Handling Instructions for Collecting and Storing Breastmilk:

  • Store breastmilk in clean, BPA-free containers intended for breastmilk 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 breastmilk 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 breastmilk. 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 breastmilk 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 breastmilk.  To avoid this from occurring, scald the breastmilk (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 breastmilk.  It causes hot spots that can burn your little one’s mouth.  Microwaving can also change the composition of breastmilk.
  • 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 breastmilk guidelines for premature babies.

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












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

93 thoughts on “Collecting & Storing Breastmilk

  1. Do you sell the cooler storage bag with ice pack separately? I have a Pump-in-style Advanced and I have no idea what happened to my little cooler bag! I’d like to replace it but cannot find the product on your site. Thanks!

  2. When bringing bottles breast milk on the go in the cooler bag, what are the feeding instructions? Do the bottles need to be heated?

    • Hi Cristina,

      Breast milk does not necessarily need to be warmed. Some moms prefer to serve at room temperature, and some moms serve it cold. You can heat breastmilk by first heating water in a cup or other small container, then placing milk in the water to warm, or you can also use a bottle warmer. Never microwave breastmilk.

      Hope this helps! If you have further questions, our Lactation Consultant would be happy to help:


  3. Pingback: Breast Pumping Tips From An Exclusive Pumper - The Vintage Modern Wife

  4. Hi

    I have Medela frestyle pump and I got a cooler bag with 1 ice pack in it. If I keep the bottles in this bag with ice pack , while getting back from work, can I freeze it after reaching home? I intend to use the milk I pump while at work for the next day’s feeding. My commute time is about 60 minutes so will it be ok to use the cooler bacg during that time?

    • Hi Sona,

      Yes, absolutely. It’s safe to use all storage techniques in succession – so milk that’s stored in a cooler can then be put in the fridge or freezer. Freshly expressed breastmilk can be stored in a Medela Cooler Bag with an ice pack for up to 12 hours. Hope this helps!

      – Kathy

      • Kathy,
        Can I pump at work- store in cooler bag all day then move to the fridge at home and then freeze within 3 days? I am not sure if since starting in cooler bag you need to freeze right away?


        • Hi Jessica,

          Thanks for your question. It’s safe to use all storage methods in succession – so freshly expressed milk can be stored in a cooler, then moved to the fridge, and then frozen.

          Hope this helps!

    • Hi Amanda,

      It depends on your freezer settings, but it should take anywhere from 3-6 hours to freeze an ice pack completely. We recommend freezing them overnight if possible. Hope this helps!


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