Breast Milk Storage Guidelines

Breast Milk has live properties such as antibodies within it to help protect your babies immune system. Because of the importance of these special components, the storage of your expressed breast milk is critical. Below is an easy table to guide you on the correct protocol and guidelines to consider for Breast Milk Storage.


Room Temperature(66-72 degrees F):                 4 hours

Cooler with frozen ice packs (59 degrees F):     24 hours

Refrigerator (32-39 degrees F):                              5-7 days

Self contained freezer (below 32 degrees):        3-4 months

Deep Freezer (0 degrees F):                                     6 months

Thawed breast milk that has been previously frozen can stay in a refrigerator for 24 hours only. It should never be stored in a cooler or at room temperature. It is also very important that you never refreeze thawed milk. It is best to store your expressed milk in 20z increments so that you don’t waste any residual milk after a feed. You will find that your milk is like “liquid gold” you hate to throw any of it away. However if your baby has only finished a portion of the bottle, you must discard the rest. See the post, The Breastfeeding Friendly Way to Bottle Feed for proper instructions on bottle feeding the baby as well as the appropriate way to heat up a bottle. It is not recommended that you add freshly expressed breast milk on top of already frozen milk in the freezer as the temperature difference can cause a break down in the breast milk properties. Instead cool down the milk in the refrigerator first. Ideally freeze the milk in a separate container, but if it is a small amount, it is okay to add once the temperature has reached between 32-39 degrees F.

***Special note:  Expressed milk, with time, will separate upon sitting. The fat and protein properties will float to the top, and the water will separate to the bottom. This does NOT mean the milk has curdled or gone bad. It is perfectly normal for the milk to do this. DO NOT THROW IT AWAY! Simply shake the milk after warming it,  it will mix well and be perfectly fine to feed to the infant.

If your milk does sit out too long, without properly being stored however, it can spoil. Just like how cows milk has a very sour smell and taste, so does rancid breast milk. Human milk that has gone bad has a very soured taste and a rather pungent odor. If your expressed milk does not smell fresh it does not necessarily mean it has spoiled, it may have to do with how the milk itself is being stored. It might be helpful to go through and evaluate what steps you are taking to store your milk correctly.

  1. Storage Containers:  Use plastic or glass bottles that have been properly sterilized, milk storage bags designed to protect the components of breast milk.
  2. Temperature Correct: Make sure the temperature of the refrigerator and freezer are set correctly. Store the milk in the back of the fridge or freezer rather then in the door where temperatures are typically warmer. Make sure your door closes, as sometimes this can lead to freezer burn and result in improper freezing
  3. Keep is Sealed: If the storage container isn’t sealed tightly it can cause odors from other foods to seep in, interfering with the freshness of the milk. Try keeping baking soda in your fridge to minimize unwanted smells.

If you still are having a problem with your milk not appearing as fresh, it could be due to an over production of an enzyme called lipase that is naturally found in human milk, and is responsible for the break down of the milk proteins. This tends to give the milk a “soapy” taste and consistency.  For protocols on how to treat this condition contact your Lactation Consultant or follow the instructions in the post: Lipase

Copyright© 2011 Danielle Gauss/ All Rights Reserved

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16 Responses to Breast Milk Storage Guidelines

  1. Katherine says:


    What advice do you have for me as I have previously thawed my milk in refrigerator and when it has been due for my baby’s feed, I then sit it in warm water before giving it to her. Though I have experienced she’s fallen asleep, so I’m left with thawed ready milk that has been warmed! I’m just a bit confused to whether I can put it back in the fridge again and warm it up in water within the 4 hour period or is it still safe to keep it in warm water for a period of time or out in room temperature?! Please help 🙂

    • Admin says:

      Hi Katherine! I would maybe suggested thawing and warming the milk about 30 min earlier so that it would be ready for her when she is due to eat so that she doesn’t have to wait too long. Or maybe trying to wake her to feed, especially if she is due to eat at that time. Remember baby’s will conserve their energy by sleeping, depending on her age having her eat at her scheduled time is very important. However, the milk can stay thawed and warmed for an hour or so at room temp. I don’t recommend putting it back in the fridge as this can cause the components of the milk to change. Hope this helps.

  2. Drey says:

    I’m very angry w my fridge’s light bulb blow ..he wanted to take out the bulb.he turned off e fridge switch ..dont know from what time yesterday morning say 10am..

    he forgotten to turn e switch back on till my mom realised this morning @2.30am..she turned on again..

    do u think I should discard my frozen milk?I’m am so mad cried and screamed and shouted at him this so mad now I cannot slp although I’m tired.

    some of.the packet milk nearer to the front has soften alittle as in partially thawed slightly. Its been more than 12 hrs since e fridge was turned off..I donto know what to do..I do not know about e rest of e froZen milk my mom said don’t open.e fridge door anymore to worsen things so I didnt check alrdy

    • Admin says:

      Oh no I’m so sorry to hear that happened. If the milk is still frozen it is still usable. If the milk has thawed it must be used. So I would recommend feeding the baby what had thawed and pumping to restore your supply. However once it is thawed you can not refreeze just like you can’t re freeze heated milk. Hopefully most of your supply was saved.

  3. t strasser says:

    Hello my baby is turning 10 mths in a few days. He is my 3rd exclusively pumped baby..But this is a first for me.. recently i noticed a decrease in doesn’t smell as sweet as it used to and that’s not even being refrigerated yet.. its kinda sour..and he drinks it fine but has been spitting it up after not sure whats going on because there has been no change in diet and its not a soapy smell like lipase describes ..please help..tryung to make the one year mark..but i dont want to make him sick.

    • Admin says:

      IF it is a lipase reaction, it wouldn’t smell like soap, it would smell sour, but have a “Soapy” look to it. Meaning, it would look shiny and greasy. If this is in fact happening, it happens when the air hits the milk. It wont make the baby sick, he just may not like it. I have an article on lipase and sour milk that will help give you more information on what you can do to help treat that. New medications or vitamins can also cause a reaction in your breast milk, so I would double check any of those as well.

  4. Jennifer says:

    Are you able to take milk from cooler or refrigerator to freezer if it is within 24 hours?

    • Admin says:

      Yes. Breast milk can be kept cool in the fridge for 4 days before being placed in the freezer. Room temp for 6 hours, fridge for 4, freezer for 3 months. Hope this helps.

  5. Dina says:

    Hi- I have pumped milk stored in the fridge for over 10 days now. I was meaning to use before but then had changes in plan and BF my baby instead. I checked the smell of the 2 bottles and they don’t have any bad odor, not even a smell. Can I use these 2 bottles or should I discard? Thanks.

    • Admin says:

      Hopefully you were able to discard the bottles. Milk should only stay in the fridge for 4-6 days, and then be frozen. So sorry you had to toss some of it!

  6. Fresh says:

    I have an 11 month old baby and an ample supply of frozen milk which has been kept in a deep freezer. In some cases frozen milk dates to February of this year (8 months ago). The reason I haven’t used it is that I’ve been giving the baby my freshly pumped milk (ie she drinks what I pumped the day before). I’ve realized that some of the frozen milk may expire but I also read that (1) fresh milk is best because the freezing process doesn’t interrupt the antibodies; and (2) breast milk content changes over time depending on the age of your baby so the frozen milk from 8 months ago was more appropriate for a 3-month old baby, whereas the milk I’m currently producing is best for an 11-month old. Do you recommend I use the frozen milk or continue with fresh? Thanks!

    • Admin says:

      Excellent question!! I would not use any milk older then 6 months, as that has already expired. You can really only keep it in a deep freezer for 8 months. That being said, you are correct that the composition of the milk does change as your baby gets older. The fat and protein ratios change. It would be fine and safe to give the frozen milk, as it still has wonderful properties for your baby, and since the little one is 11 months old, baby is most likely on solid foods and therefore would be just fine with the older milk. It really is your call. If you have enough to give of the fresh without running out, then go for it as it is more age appropriate, but the milk that has been frozen for 6months is just as good/safe for him to drink. Best of luck to you!! Well done!

  7. Alexandra says:

    Okay, so you say not to store thawed breast milk that was previously frozen in a cooler or at room temp, so what do I do if I am going out and want to take a bottle with me and all I have is frozen milk and my daughter may not want to eat right away? How do I store it then because it would either be at room temp, or stored in a cooler if I brought it with me. Why do you suggest not keeping it either of those ways?

    • Admin says:

      You can store the milk in a cooler that is fine. You just can’t refreeze and reuse the already thawed milk. The reason being is that the milk properties change and it could spoil. But taking it frozen into a cooler would be the best option, or keeping it in a cooler once cold is fine also. Hope this helps.

  8. Stephanie says:

    Hi I was wondering if I pumped 3 hours ago and forgot to put in my fridge will it still be good if I do it now? I know it can sit out for 4 hours but didn’t know if you can store in the fridge after is sat out for a few hours?

    • Admin says:

      Yes you are okay to put it in the fridge. It can stay in room temp for up to 6 hours before going in the fridge.

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