BreastfeedingDonating Milk

Dos and Dont’s of Storing Breast Milk

Do’s and Dont’s of Storing Breast Milk

Editor’s Note: This was originally published in March 2014 & has been updated to provide you with the most current content. Fun fact – this was our most popular blog post of 2020!


Did you know, when milk storage bags leak, not only is milk lost in volume but the composition of the milk is changed such as fat, protein, and nutritional content?

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Proper milk storage is also a matter of safety, because if your bag has a hole or is not sealed properly it is possible for germs and bacteria to get into the milk.

When it comes to milk donation, if storage bags are not properly labeled we will be unable to use the milk for donation. We highly value our milk donors and want them to be confident that all their milk is being used!

Bags that are not labeled become a safety concern due to the volume of milk and number of donors we may receive at any given time. The guessing game of “Who’s milk is this?” is not a risk we can take when it comes to feeding our fragile babies.

Proper milk storage not only helps us provide safe donor milk for fragile infants, but will also help you know that your own baby is getting the best of your milk.


  • DO include first and last name of mom or baby, date (mm/dd/yy) milk was pumped, and donor number if known. Estimated number of ounces is always a bonus!
  • DO be sure to fill bags only to the maximum amount listed on the bag! 5 ounces is preferred.
  • DO store bags as flat as possible in your freezer.TIP: Store bags in a plastic storage bin, shoe box or another container in your freezer. Some moms even use a separate container to store milk in order by earliest date frozen.
  • DO be sure to remover any excess air before zipping the bag closed.
  • DO be sure to zip your bags and double check they are completely sealed- this is important!
  • DO keep a permanent marker in your pumping bag and mark the storage bags as they are filled. We know sleep deprivation is a real thing and we want to make sure your milk is accurately labeled and dated.

Do you use technology to keep track of your freezer stash? We found a great article that compares apps for keeping track of pumping and inventory. If your favorite isn’t on the list, message us on social media to give us your recommendation!


Dos & Don'ts of Storing Breastmilk {}


Dos & Don’ts of Storing Breastmilk {}

  • DON’T store bags on their side, tightly against other items, or against the freezer door.
  • DON’T overfill the storage bag! Please only fill the bag to its maximum capacity. As milk freezes, it expands…a lot!  Bags that are too full will most likely burst at the seams or tear.
  • DON’T forget to double check that you have labeled your bags before donating.
  • DON’T overlook general hygiene, hand washing, and sanitizing your pumping parts.

Check out our other resources for breastfeeding parents and milk donors on our website! If you would like to donate your extra breast milk, our pre-screen is now online!

Tags: Breastfeeding, Donating Milk

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