Wondering how to store breast milk? Here’s everything you need to know about storing breast milk at room temperature, in the refrigerator, and in the freezer.
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Once you’ve pumped your milk, what do you do with it? You can:
- Feed it to your baby at the next feeding
- Store it in the refrigerator
- Freeze it
Below are summaries and best practices regarding each of these options.
Storing at room temperature and feeding fresh milk
One option that can be easiest when you’re exclusively pumping or pumping to feed your baby in the next few hours is to keep your milk at room temperature and feed it fresh.
This is pretty straightforward – once you’ve finished pumping, you can set it aside and then give it to your baby when he or she is hungry.
How long can breast milk stay out?
Freshly pumped milk can safely stand at room temperature for at least 4 hours. (Slightly longer – up to 6 to 8 hours – may be acceptable depending on the ambient temperature.)
Reusing expressed breast milk
What if your baby starts a bottle, but doesn’t finish it?
You can offer it again within two hours of when baby finished the first feeding.
What should you do with the milk during those 2 hours? Some parents choose to leave the milk at room temperature, and others prefer to refrigerate and rewarm. Because no studies have been done, we don’t know which is better.
Storing in the refrigerator
Breast milk storage guidelines for refrigerated milk can vary quite a bit. The CDC says breast milk in the fridge is fine for 4 days, while other sources will say up to 8 days. If possible, I would aim to use or freeze milk in the fridge within 3-4 days.
If you have a number of bottles in the refrigerator at any given time, it is a good idea to label them with the pump date (you can use a piece of masking tape or a dry erase marker) or order them with the oldest bottles in front so that they are used first.
Mixing breast milk is fine. Treat the mixed milk as if it was all pumped on the first pump date/time.
Over time, cream will rise to the top of the milk as it is stored in the fridge. This is normal and nothing to worry about.
The pitcher method
If you’re exclusively pumping and have a lot of bottles in your fridge, you may want to try the “pitcher method.”
This just means combining all the milk that you pump in one day into a large container (like a Dr. Brown’s pitcher or mason jar).
Then, at the end of the day, you prep bottles for the next day and freeze any extra milk.
More on the pitcher method here.
Warming the milk for feeding
When you are ready to feed your refrigerated milk to your baby, you may need to warm it. (Cold bottles are fine if your baby will take them, but many will not.)
There are a few different ways you can do this:
- Use a bottle warmer
- Put it in a container of warm water
- Run it under warm water in the sink
Never microwave breast milk or formula, as the microwave can create “hot spots†that will burn the baby’s mouth, and make sure to check the temperature after warming by squirting a bit on your wrist or hand.
Freezing breast milk
Frozen milk can be stored in most freezers for up to 12 months, though the CDC says up to 6 months is ideal. (The CDC used to have different guidelines for regular freezers and deep freezers, but they no longer distinguish between the two.)
If you’re freezing milk in the freezer compartment of a mini-fridge, that should be used within 2 weeks.
If you have frozen milk that you’re not sure is still good, you can test it with MilkStrips. (More on these test strips here.)
How frozen milk should be stored
Breast milk can be frozen in glass or plastic bottles or breast milk storage bags. If you have a small freezer stash, you might want to use reusable breast milk bags; if you are building a larger one, you’d want to use disposable bags.
When freezing the milk, label it with:
- The date the milk was pumped (if you have milk from more than one pumping session in the same bag, use the earlier date). You can include the time the milk was pumped as well, but this is usually less important.
- The amount of milk in the container.
- Your child’s name (if your child will be using the frozen milk in a childcare setting).
How much milk should you freeze in each bag?
There is no correct answer here – you kind of have to figure out a system that works for you.
Many sources recommend storing milk in 1-4 oz portions so you don’t waste milk. This will work fine – if it turns out you need to thaw a bag with more milk than you need, you can thaw it in cold water and store the rest for later. You’d just need to use it within 24 hours.
When should you start freezing milk?
This also doesn’t have one correct answer. I would suggest starting to freeze your milk whenever you have a little extra that you won’t need in the next few days. (If you’re wrong and you do need it, you can always thaw it and use it.)
More on when to start freezing milk here and how much you want to store here.
Using frozen breast milk
There are a few different ways that you can thaw milk:
- Put the milk in the refrigerator to thaw slowly (it will take about 12-24 hours)
- Place the milk in a container of cold water
- Put the milk in a container of warm water (thaws and warms the milk at the same time)
If you plan to use only part of the milk in the bag, or if you’re defrosting for a later feeding (for example, if you’re prepping bottles for the next day’s childcare), you’ll want to thaw the milk in the fridge or in cold water. Otherwise, warm water can be easiest since there’s no separate warming step.
Frozen milk should not be thawed at room temperature.
More on defrosting breast milk here.
How to use milk once it’s thawed
Once frozen breast milk has been thawed, it should be used within 24 hours.
Frozen milk should not be refrozen.
Rotating frozen milk
A few weeks after you start freezing milk, consider starting to rotate your milk. This just means using the oldest milk in your freezer for a feeding, and replacing it with the milk that you would have fed your baby.
Before building up a large freezer stash, it’s a good idea to give your frozen breast milk a test run with your baby. This is just to make sure that you don’t have a lipase issue.
Storing breast milk in a cooler
Breast milk can be stored for up to 24 hours in a cooler. (More on breast milk coolers here.)
If you need to travel with fresh or frozen breast milk, here are some tips for packing your breast milk.
Do you have any questions about how to store breast milk? Ask them in the comments!
References
- CDC. “Proper Storage and Preparation of Breast Milk.” https://www.cdc.gov/breastfeeding/recommendations/handling_breastmilk.htm
- Bonyata, Kelly, IBCLC. “Human Milk Storage.” https://www.kellymom.com/store/freehandouts/milkstorage01.pdf
- Bonyata, Kelly, IBCLC. “Reusing Expressed Breastmilk.” https://kellymom.com/bf/pumpingmoms/milkstorage/reusing-expressedmilk/
Hi, the info you provided is great! I’ll be flying without my baby for the first time and the whole trip will be about 10 hours. You said you can store up to 24 hours in a cooler. Do it need to maintain fridge temp? (I have a thermometer) or just need to be cool? Also if I use ice in a cooler, would that freeze the fresh milk? Thank you.
Hi Amity! The CDC says 59 degrees or cooler. Ice shouldn’t freeze the milk. Hope that helps and have a great trip!
I’m pumping for a caregiver to feed my baby while I’m at work but breastfeeding on nights and weekends. Is it best to freeze milk I’ve pumped on Fridays or just keep in the fridge for Monday’s feedings since it’s less than four days? I’m using the pitcher method and it’s working great so far.
Hi Jenise! You can really do it either way. I just kept it fresh because it was easier, but either way will work! 🙂
Hi! I’m exclusively pumping and having a hard time determining the best “rotation” schedule in and out of the freezer. I freeze every 3rd day of the week but am now getting to a point where I still have too much in my fridge that we’re not getting through fast enough AND a huge supply in the freezer that I’d like to rotate in. I want to have the “freshest” milk in the freezer when my supply drops off to get my through the remainder of his first year. I haven’t been able to find a ton of resources on rotation options. Can you recommend a schedule?
Hi Kallie! A lot of people do one frozen bottle a day or pick a day to feed frozen milk (like Frozen Fridays). I would try one of those out and see how it works for you!
Hi Amanda! Is there harm with air bubbles in frozen milk bags? I can’t seem to get all the air out without pushing some of the milk out. I’m freezing 2 ounces in 4 ounce lansinoh bags but thinking I should freeze 3-4 oz to help eliminate as many air bubbles as possible. I already see crystals forming where the air bubbles are in the bags. Thanks!
Hi Janelle! No, it’s not problem. You want to get as many out as you can to save space, but it’s no big deal. 🙂
This blog is FANTASTIC and exactly what I have been looking for! Thank you for all your information. I have a question in general about the guidelines. I am not sure how to word it but I will just try my best. So if I have breast milk in the fridge…it can be in there for 3-4 days (best practice). If I do not use it in 3-4 days, is it then safe to freeze?
Also, I will be traveling by car soon. If I put frozen breast milk in a cooler, can I just put it back in the freezer when we get to our cottage and then treat it like normal frozen breastmilk? Same with refrigerated…if it is in a cooler for travel…I know it’s good for 24 hours in the cooler…but then is it still good for 3-4 days in the fridge at my destination?
I am so sorry that is so confusing…just trying to figure out how the guidelines work with crossover type situations. New momma…sorry so wordy!!
Hi Christina!
So to answer your first question – yes. if it hasn’t gone off (and it wouldn’t have in 3 days) then yes, you can freeze it. Just freeze it as soon as you know you won’t be using it soon.
Yes, that should be fine. As long as the frozen milk stays frozen, you can put in the freezer at the cottage and treat it like normal frozen milk. Same with the cooler – but I’d keep it as cold as possible and use it as soon as you can. (Just like, use that first, versus feeding fresh milk and keep the cooler milk in the fridge for days.) But that’s more of a best practice than a rule. The CDC doesn’t go into all these hypotheticals!
Thanks for all your info and tips and tricks! If I’m pumping and will feed to my baby within 4 hrs of pumping, will the milk retain more nutrients and “superpowers” if I keep it at room temperature, or if I refrigerate it and warm it up with a bottle warmer? My baby will drink at room temperature, but not at fridge cold. Just wondering what makes the most sense! Thanks!
Hi Christi! I’m not sure the research has been done on what exactly happens to the levels of antibodies and nutrients in terms of warming. Overall, i would say do what is easiest for you, as the difference will likely be minimal and a trade off – the refrigerated milk would have less bacterial growth but the milk that wasn’t warmed might have slightly more antibodies. Again, this is going to be a very minimal difference so just do what works best for you!
So I pumped 5 oz and refrigerate it and I’m not sure how I’m supposed to feed it to my baby ? Can you help me by explaining how I should feed him that milk ? he usually drinks around 2-3 oz per feeding
thank you
Hi Esme! The next time baby needs a bottle, I would put 2-3oz in a new bottle, warm it (if baby likes bottles warm), and feed. Then you can feed the rest of the pumped milk the next time baby needs a bottle. If it won’t be for more than a few days, I would freeze it. I hope that helps!
Hi, i just had a baby about a week old now…i’ve been having issues with the baby not latching on and/or not producing enough milk so I’ve been supplementing with formula and pumping about every two hours for 20 min. I’ve been storing my freshly expressed milk into breast milk storage bags and then putting them in the refrigerator. My question is what is the safest way to store the milk each time I pump…do I keep pouring it in the same bag at room temp then refrigerated it or do I refrigerate it first to chill then out it in the same bag?
Erika
Hi Erika! Congrats on your baby! Refrigerate it first so that it’s the same temp as milk that’s already chilled, then combine! 🙂
If I am traveling by car with breast milk in a cooler, As soon as I get to my destination is it safe to then put the milk in the refrigerator? If so, how long would it be good for?
Yes that’s fine. As long as it was in the cooler for less than 24 hours, you can follow normal guidelines for the fridge.
Why should you not thaw frozen milk at room temperature? I have been leaving out a few bags but put them in the fridge before completely thawed (still very cold, almost slushy)
I’m honestly not sure, as the CDC hasn’t (at least as far as I know) given a reason for this guideline?
Hi Amanda, your blog is amazing and so so informative. Thank you!
I have read over and over again that frozen breast milk should not be thawed at room tent; however no one has been able to explain the rationale for this. Can you help here.
Hi! Thank you! I can’t explain the rationale for it because I don’t understand it either. It’s a great question that I would love the CDC to explain!
If I pump after baby nurses and only get 2 oz, can I dump that in with the 4 oz I have in the fridge from when I pumped earlier in the day?
Hi Laci! You can, just chill it before you dump it in.
Hi Amanda,
I have a bottle that was in the refrigerator which I wanted to freeze. I ran it under hot water to break up the fat and then left the bottle in a cup of warm water. I forgot about it and came back 10 minutes later. The milk is now warm. Is it okay to still freeze it? Thanks!
Hi Toyin! No, I’m so sorry – it should be used within 2 hours of being warmed. Sorry for giving you bad news!
Great article! If I thaw frozen milk, warm it, and baby does not consume the whole bottle. Can I refrigerate and reuse/rewarm the rest similar to refrigerated milk? Or is the fact it’s previously frozen mean it’s a one use and done bottle?
Thanks,
Maria
The CDC doesn’t make a distinction between refrigerated and previously frozen. 🙂
I know you can’t combine freshly expressed milk with refrigerated milk but can you pour freshly expressed milk into a a cold glass jar that has been in the fridge?
Yes, I see no reason that would cause any issues, assuming the glass jar is clean!
Hi Amanda,
My baby was born preterm so I’m exclusively breast pumping at the moment. Whatever I pump at the NICU stays there what I pump at home stays in my freezer. I have a question though, once my son starts requiring more then 2 oz is it ok to defrost milk from that particular day and combine it together for his feeding? It’s something that I haven’t been able to get clarification on. Thank you in advance!!
Natasha 🙂
Yes, that’s fine. You can combine milk from multiple sessions for a single feeding. Congrats on your sweet baby!
Hi Amanda,
Can I refrigerate the baby’s unfinished breast milk and can reuse after few hours or even if I refrigerate it should be under 2 hours ??
Madhura
Hi there! Even if you refrigerate it, it should be under 2 hours. Hope that helps!
Thank you! Your site has been invaluable with information when I chose to exclusive pump for my 6 week old. At the moment I am pumping just a little more than what baby drinks. I’ll pump 3.5 to 4.5 oz while baby drinks about 2.5 to 3.5. I typically put aside 1 oz before feeding so I don’t waste anything. Any suggestions on how to reduce waste and what to do with the extra 0.5 to 1 oz that I don’t end up giving to my baby?
Hi Jen! I would combine that 0.5/1 ounces in a separate bottle each day, then freeze it each night!
Thank you for the reply! Is It okay to mix freshly pumped breast milk with refrigerated breast milk? When I tried to mix two refrigerated ones together I struggled to get the fIlm/fat? on the side of each container to mix
Hi Amanda – thank you for all this amazing information on your site. this may be a silly question. Do I need to let me pumped breast milk cool before storing away in the refrigerator? I usually cap and store it quickly in the fridge, but noticed a lot of water droplets form afterwards.
Thank you!
Hi Jenny! No, what you’re doing is fine!
Hi Amanda, love your site, have used it for two babies now. I started storing extra milk in the fridge (life 1 – 6 days now) and newborn baby doesn’t need it, it is okay to still transfer it all to the freezer now for the future? Thanks! Michelle
Yes! Do it as soon as you know you won’t need it, but as long as it’s within the guidelines that’s fine.
Hi! My baby has transitioned the cup and is happily drinking cold milk. If the milk is still cool when she is finished, can I put the cup in the refrigerator and use it for the next feeding? Could you explain the feeding rules of using chilled milk? Thank you so much!
Hi Nikki! You can use it for 2 hours after baby starts drinking it. 🙂
Hi!
When freezing my sons milk, we always used breast milk bags but we cut the info tab off because we had some leaking issues and found it easier. We would write the date with a sharpie on the bag itself – was this a mistake? Can we still use the milk or do you think the sharpie could have contaminated the milk?
Thanks!
Hi Sarah! While I don’t know for sure, I think this is most likely okay – I have seen many people decorate breast milk bags with sharpies on social media (and Kiinde, who makes bags, has shared them, which I assume they wouldn’t do if this is an issue). If you’re concerned you could ask the bag manufacturer if this is a possibility?
Hi! I have a quick scenario question about using frozen breastmilk. I have been exclusively pumping since the end of January, but have yet to use my stash (I realize I should have tested it before now – whoops!) Right now, I take my freshly pumped breastmilk out of the fridge a couple hours before my baby eats so it has a chance to warm up slightly. Can I do the same thing with frozen breastmilk? For example, can I first thaw frozen breastmilk in the fridge (I know it takes about 12 hours), and then let it sit at room temperature for a couple hours to warm a bit? Or is this a no no?
Thank you!
Jaclyn
Hi Jaclyn! I have searched everywhere for this question and can’t find an evidence-based answer. I would probably default to leaving it in the fridge and warming it as a result. Sorry!
Hi Amanda – For some reason I was not able to reply to your comment so I am replying to my own comment. Thank you for looking into it! I could not find any information either.
Hi there,
I see many have asked the question about being able to still use a bottle that was refrigerated, warmed but never drank from. I see you have stated the CDC day it must be consumed with in 2 hours. Do you happen to know why it can’t be re-refrigerated and heated up again? I under stand when it’s been drank from with possibility of bacteria but if it never touched the baby’s mouth what’s wrong with it?
Thanks for any input
Hi Caren! It’s because the warming process allows bacteria to grow more quickly. I don’t know why 2 hours is the guideline they chose but that is the logic behind it. Hope that helps!
Hi Amanda, May I know if it’s alright to leave freshly pumped milk at room temperature for around 3 hours before refrigerating it?
My understanding is that that’s okay. 🙂 I would refrigerate it as soon as you can though.
Hello!
my milk supply has increased a lot, my lo is one weeks old & takes 2oz every feeding.
i usually pump 5 to 6 ounces i store it in the fridge and only take the 2oz out & put the rest back, wondering of thats safe?
Hi America! Are you taking the 2oz out, putting it in a different bottle, and feeding it? If so, that’s fine! If you’re feeding in that bottle and putting it back, the rest of the bottle should be used within 2 hours.
Hi Amanda,
Is there a must to store frozen milk in a separate deep freezer that is used for storing milk and milk only?
Any documented cases of cross-contaminated with other food that you have come across?
Many many thanks!
Linh
Hi Linh! Not that I know of!
uestion: I will put milk from fridge in bottle, warm it up. I always fill bottle to 6 oz, he will take 4 usually (up to 6 at times so I always fill to 6) so I usually have 2 oz leftover. Put 2 oz in bottle back in fridge, and then add 4 more oz cold milk and reheat. Is this ok? How often can I reheat that same bottle? I’ve heard twice. So for example if I’ve reheated that bottle twice but there is still milk leftover at the end, do I have to get rid of it? What are the current recommendations? Thank you!
Hi! I would just put 4oz in the bottle instead and warm more up if he ends up taking more. I wouldn’t keep doing it as you’ve described – there is the chance for bacteria to grow in the leftover milk. I hope that helps!
Hi Amanda! Thanks so much for all of the helpful information 🙂 I was wondering if you know- I have used all of the available space in our inside freezer and garage freezer so I bought a deep freezer today to transfer all of the milk into that. Do you know if it will then be good for up to a year or still only the 6 months?? Thanks so much!
Hi! It depends on how long it was in the other freezers and how often you opened the doors of the other freezers. If you had it in there for a few weeks and rarely opened the doors, probably closer to a year. If it was longer and you opened the doors frequently, you might want to keep it for a shorter amount of time.
Hi Amanda, i’m mother of a 10 week girl and started exclusive pumping a week ago. I’m so glad that i found your page, so much useful information for a new pumper like me. Thank you so much.
I prefer to feed my baby with freshly pumped milk and put any extra in the fridge. By the end of the day, i collect all the extra and put into the freezer. My question is what is the expiry date of the frozen milk now? Is it a full 3 months or should it be 2 months only as a third of its shelf-life has already passed in the fridge (given the shelf-life in fridge is 3 days).
Thank you again for your hardwork!
Hi Ha Bui! It should be fine for the full time, I’ve never seen any experts suggest discounting the time based on fridge time! 🙂
Hi Amanda, I warmed up a bottle of fresh breast milk that wasn’t refrigerated but my baby didn’t want to drink it. The milk never touched his mouth. How long is it safe to keep this milk? Can I freeze it?
Thanks!
It’s only good for 2 hours according to the CDC unfortunately!
Hi! Can I re-refrigerate milk that was in the refrigerator and warmed but not consumed?
Hi Misty! You can but the CDC guidelines state it should be used within 2 hours of being warmed. (So you can re-refrigerate and re-warm, but only within 2 hours. You can also leave it at room temp.)
I took a refrigerated bottle and warmed it for my baby. She didn’t drink it all. Must she drink the rest within 2 hours before discarding?
That’s what the CDC recommends. 🙂
Hi Amanda,
if I take out the milk from refrigerator, under room temperature, how soon my baby has to consume it please?
Thanks again!
Hi Rena! About 4 hours.
My little guy is having trouble gaining weight, so they’re having me pump after nursing and offer him the pumped milk. My question is can I still save and freeze what he doesn’t take? Or do I have to discard it since it touched his mouth?
If it’s in a bottle he drank from, you have to discard it. You could try offering smaller bottles, and then freeze any milk you don’t offer?
Can you take milk out of the refrigerator and set it on the counter to “warm up” before your next feeding? IE: middle of the night feedings to take a bottle out after a feeding to be used at the next one in 3-4 hours? I have not been, but curious if there’s guidelines on if you can safely do this. My LO seems to spit up cold milk.
You can. I answered this with more detail here! 👍
https://exclusivepumping.com/can-i-feed-my-baby-this-breast-milk/
Hi Amanda, can I transfer the milk to freezer after set in the refrigerator for 2 days? Thanks!
Yes you can! 🙂
Hello,
Thank you for providing all this info with pumping. It’s a great resource. I have a question about frozen breast milk. I need to transfer my frozen breast milk from my in-laws deep freezer to my refrigerator freezer to be used within a few days. Is it safe to do so? I have found lots of info from freezer to deep freezer but not vice versa.
Thanks,
Marina
As long as you’re using it within a few days it’s fine. 🙂