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.

68 thoughts on “Collecting & Storing Breastmilk

  1. I’m planning on traveling soon and want to bring frozen milk with me so my parents can use it for my baby while my husband and I attend a wedding. Will it stay frozen in a cooler during cross country travel?

    • Hi Jennie – You can safely keep your milk in a cooler with 3 icepacks for 24 hours. Then, it can be refrigerated for 3 to 8 days. Safe travels!

  2. I’ve been freezing my BM for 2 months in a normal two door fridge. If I move them into a deep freezer can it still last for another 4 months? Or only those that we directly store into deep freezer can last for 6 months.

    • Hi Emily – We only recommend keeping your milk in the deep freezer for 6-12 months if the milk started out in the deep freezer. If it was stored in your refrigerator freezer it will be good for 3 to 6 months. We hope this helps!

  3. Is it better not to put milk in the fridge (room temp 25 degrees celcius) if the baby will consume it within 12 hours?

  4. I don’t want to use a fridge at work when I return for storing breastmilk. If I use the Medela cooler bag to store milk I express during the day (with ice pack from freezer when I leave the house in the morning). How long can I store the milk in the cooler bag and does this mean I need to use within certain time or can still store thereafter in the fridge or fridge as normal?

      • Hi Adri,

        Freshly expressed breastmilk can be stored in a Medela cooler with ice packs for up to 12 hours. It can then be transferred to the fridge for 3-8 days, or the freezer for 6-12 months. All of the breastmilk storage guidelines can be used in succession – so you can move breastmilk from a cooler, to the fridge, to the freezer while following the timing recommendations listed above. Milk that has been frozen and defrosted should be used within 24 hours, and cannot be refrozen.

        Hope this is helpful! Let us know of any additional questions. Thanks!

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