If you’re a pumping mom – whether you pump exclusively, while away from your little one, or for the occasional night out – you work hard for every last ounce you pump, which means you probably cringe at spilling even a single drop of milk, much less having it spoil or go unused.
The good news? Expressed breast milk is quite durable, and there are only a few situations where you’d definitely need to toss your liquid gold.
Instead of spending your nights researching "How long does breast milk last?" or "When does breast milk go bad?" read our guide to storing and feeding pumped breast milk.
How Long Does Breast Milk Stay Fresh…
…In the fridge?
Mother's milk can be stored in the fridge for 4-5 days; 72 hours or less is optimal. For best results, store your milk in the back of the fridge so it stays cool.
…In the freezer?
If your freezer has its own door, 3-6 months is fine. Your milk can stay fresh for 6-12 months if you store it in a separate deep freezer. In all cases, store the milk in the back of the freezer. If your freezer shares a door with your fridge (rare these days but possible), you should use your breast milk within 2 weeks of freezing it.
…Once I’ve moved it from freezer to fridge?
…On the kitchen counter?
At room temperature (around 70 degrees), breast milk can be stored for about 4 hours. If the milk was freshly expressed with a clean and sanitized breast pump, keeping breast milk at room temperature for 6-8 hours may be fine, especially if the room is colder. Refrigerate your milk if you think it won’t be used.
…In a cooler or on ice in my pump bag?
…If I’ve warmed it but didn’t use it?
According to the CDC, warmed milk should be used within 2 hours after you’ve heated it. There’s no published research about whether you can then safely store it in the fridge or freezer. (Note on warming milk: Make sure you don’t put the milk itself into the microwave. Instead, microwave a bowl of water, and when it’s finished heating, place the milk container into the warmed water.)
…After my baby has drunk from the bottle?
When your baby drinks from a bottle, bacteria enter the bottle. Although more research needs to done on this matter, experts recommend using the milk within 1-2 hours (whether it’s stored at room temperature or in the fridge) and then discarding it afterward to prevent bacterial growth. Storing your milk in small amounts helps avoid waste if your baby doesn’t finish the bottle.
Is My Breast Milk Still Good If…
…It’s in the freezer and the power has gone out?
If your power’s out for a short time, your frozen breast milk is probably fine as long as it still has ice crystals in it. If your power will be out for a while, make sure to pack your freezer tight. Then, don’t open the freezer unless absolutely necessary. If your milk has completely thawed, it must be used within 48 hours and can’t be refrozen.
…It’s in the fridge and the power has gone out?
A refrigerator that hasn’t been opened should remain cold for about 4 hours; you should consider using your refrigerated milk by then, if possible. If not, you can follow guidelines for how long milk stays fresh outside of the fridge (generally 4-8 hours at room temperature).
…It smells bad?
Refrigerated or frozen breast milk is probably going to smell a little different from fresh milk, and that’s usually not a problem (breast milk smell varies from person to person too). Human milk that has truly spoiled will smell and taste sour, like when cow's milk is spoiled, and should be discarded.
…It smells soapy?
In some cases, your milk may smell soapy, which is likely due to the breakdown of an enzyme called lipase. Some nursing mothers produce more lipase than others. There is nothing wrong with your milk, but if your baby rejects it because the milk tastes soapy, you might consider scalding (heating but not boiling) your pumped milk before you store it. This deactivates the lipase and doesn’t significantly change the nutritional content of your milk.
…It looks like it’s separating?
Expressed milk kept in the fridge will naturally separate, and you may notice a layer of fat on the top. This is totally normal!
…It’s a funny color?
Breast milk can take on a bunch of different hues, and they’re almost always normal. It can be white, deep yellow, yellowish-orange (colostrum, the first milk you produce, looks this way), and even blue or greenish.
Sometimes breast milk color changes based on what you’ve eaten or what medication you’ve taken (if you’re exclusively pumping, you may have already seen this). You can speak to a lactation consultant or pediatrician if you’re concerned about the color of your milk.
…I have thrush?
If you have thrush (candida/yeast infection), you can still pump your milk during treatment and feed it to your baby. After treatment, if you’re concerned about thrush contamination and transmission, you may consider discarding the milk you pumped while you had thrush, though it isn’t dangerous for your baby. Some mothers boil this milk to sterilize it, but that may reduce some of the nutritional value.
…I’m sick with a cold or flu?
If you’re sick with a cold or flu, remember that your baby has likely been exposed to what you have anyway – and you’re already producing antibodies to fight the illness. These antibodies are present in your milk and get passed on to your baby, which helps keep them healthy. Also, keep in mind that cold and flu viruses are not transmitted through breast milk.
What’s the Best Container to Store My Liquid Gold?
Does it matter what type of container I use?
Experts don’t recommend one particular storage container over another. Many mothers prefer BPA-free plastic breast milk storage bags because they’re easy to store in the freezer. Just make sure to label each bag with the date and amount and watch for leaking.
Glass storage containers are popular too because they’re very durable. If you’re reusing a glass jar (perhaps one that contained baby food), remember to sanitize it before using it for breast milk.
How much should I store in each container?
It’s best not to store too much breast milk in each container. That way it’s less heartbreaking if you end up having to toss some of the milk. 2-4 ounces per container is a good amount. That amount also leaves room for the frozen milk to expand.
When storing milk or preparing a bottle, can I combine milk from different pump sessions?
Yes, you can combine milk from different pump sessions/storage containers. When combining pumped milk, note the date of the earliest pumped milk, and discard based on that date.
You’ve Got This!
Sometimes you’ll have a particular question or scenario that isn’t cut and dry, and you may need extra breastfeeding support. Asking for advice from an International Board Certified Lactation Consultant (IBCLC), breastfeeding counselor, or trusted pediatrician is a great first step. There are many online resources, including the Academy of Breastfeeding Medicine (ABM), which has its own breast milk storage and handling resource.
While these breast milk storage and handling guidelines may seem a bit complicated at first, no one expects you to remember exactly when breast milk goes bad. Keeping a breast milk storage “cheat sheet” around is a fantastic idea. You can even put the guidelines on your fridge for easy reference.
Most of all, give yourself a giant pat on the back for providing amazing nutrition to your baby, all wrapped up in cuddles and love. (And don't forget to treat yourself to the best nursing clothes around. Save 20% when you use the code KBBLOG20 at checkout.)
Click here to download and print our breast milk storage guidelines: