How long can breastmilk sit out? Can you reuse milk that your baby doesn’t drink? What about re-freezing? Can you do that?
The whole process of storing, freezing, and thawing breastmilk is confusing. But if you’re a pumping mama, it’s unavoidable.
Here is everything you need to know about how to properly store, freeze, and heat breastmilk.
*This post contains affiliate links. You can read my full disclosure here. It’s pretty anticlimactic.
How Long Can Breastmilk Sit out at Room Temperature?
Great question! According to the CDC, breastmilk can be stored at room temperature (77 degrees F/ 25 degrees C or cooler) for up to 4 hours.
For example, if you thought that your baby wanted more milk, but you both fell asleep for two hours before he drank from the bottle, you’re in the clear! You can still refrigerate the milk for later use.
I should note that the Mayo Clinic says that up to six hours is acceptable, assuming that the room is not particularly warm.
Clearly there is some level of flexibility here. If your house is 70 degrees and the milk is out for 4.5 hours, it’s not like it suddenly spoiled 30 min ago.
It’s always best to play it safe. If you’re a paranoid mom (no judgement here), you will probably feel more comfortable throwing it out right at the 4 hour mark.
But if you’re not a paranoid mom (again, no judgement either way), it’s not like you’re going to poison your baby by leaving it out for up to 6 hours.
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If my baby doesn’t finish a bottle, can I refrigerate that breastmilk and reheat it later?
Bacteria transfers from your baby’s mouth, into the bottle, contaminating the milk.
According to pretty much every authoritative source, you need to throw the milk out after your baby drinks from the bottle.
I’m just going to throw this out there though- I don’t.
Why? Because I’m lazy, cheap, and can be laid back to a fault.
I like to live life on the edge. I do things like eat my eggs over-easy when I’m pregnant and let my kids smack their heads on the bottom of the table when they stand up.
To be clear, I am NOT saying that you should follow my lead in regards to re-refrigerating used breastmilk.
In fact, I recommend that you don’t. Health and safety guidelines recommend that you don’t.
But if you do follow my lead, I won’t judge you.
How Long Can I store Breastmilk in the Fridge?
Again, when we are looking to authoritative sources we get slightly different answers about breastmilk storage.
Regardless, they all agree that you should move it to the freezer within 3 days if you don’t plan on using it.
When storing breastmilk in the fridge, you should always place it in the back. This ensures that the temperature stays as cool as possible.
The worst place to store breastmilk is in the door where it will be exposed to frequent bursts of warm air.
How long can I store breastmilk in an insulated cooler?
If you have plans to travel, or you need to pump while you are out of the house, you can safely store your breastmilk in an insulated cooler with ice packs for up to 24 hours.
If you are exclusively pumping, or want someone else to take the night shift, this is a convenient way to store breastmilk overnight.
It takes less time to heat, and saves you a trip to the refrigerator.
How Do I Freeze Breastmilk?
Freezing breastmilk is pretty easy and straight forward.
First, begin by washing your hands and your workspace.
Do not use small ziplock baggies to store breastmilk.
I’ve seen this going around on Pinterest and find it extremely stupid (though I have to admit, I almost did it when my first baby was born).
Breastmilk storage bags are thick, BPA free, and pre-sterilized for safe use.
Simply dump the expressed milk from the bottle into the breastmilk storage bag. Some women use the pumping flange as a funnel to prevent spills.
Milk should be stored in small amounts to prevent waste. Between two and four ounces per bag is ideal.
Remove as much air as possible before sealing. If using a hard plastic or glass container, leave one inch of air for expansion.
For the most efficient storage, lay flat to freeze. After the bag of milk is frozen solid, it can be propped up and stored like files in a filing cabinet.
Milkies Milk Trays are a great alternative. Each tray freezes eight 1oz “sticks” that fit into any bottle.
This enables you to thaw the exact amount that you need, without the stress of wasting milk.
How long can breastmilk be stored in the freezer?
Breastmilk can be stored for:
- 6 months in a freezer that is attached to a fridge
- 1 year in a deep freezer
Never store milk in the door because of the influx in temperature.
Breastmilk should always be stored toward the back of the freezer where temperature remains consistently cool.
How Do I Thaw Frozen Breastmilk?
Once you have frozen your breastmilk, there are a few different ways to thaw it out.
- Move to the refrigerator overnight
- Set in a bowl of lukewarm water
- Place the bag (or bottle) under a stream of warm water
The slower you thaw breastmilk, the less fat and nutrients will be lost. This means that thawing it overnight in the refrigerator is ideal.
But sometimes your baby is hangry and you’re in a frenzy because there’s no milk in the fridge.
In that case, quickly thawing your breastmilk with warm water is perfectly safe and won’t hurt your baby in any way.
NEVER should you EVER heat up breastmilk in the microwave. Microwaving breastmilk kills its amazing antibodies, and worse- creates hot spots in the milk which can burn your baby’s mouth and throat.
How do I feed thawed milk to my baby?
This should be intuitive, but it’s actually not. Here are some things you should know:
- Never heat the milk in the microwave. Again, it can scald your baby’s mouth, even after it has been swirled.
- Place bottle in a bowl of warm or hot water (or a bottle warmer), but do not use boiling water. That will kill antibodies in the breastmilk.
- Swirl the milk to mix it. Never shake a bottle of breastmilk. Shaking breastmilk breaks down the proteins.
- Test the temperature on the inside of your wrist. It should be lukewarm or cooler.
- You can feed baby cool milk. There is no rule that says they have to drink it warm. In fact, if you are exclusively pumping, feeding your baby cool milk will be much easier in the long run.
- When heating milk, only heat it once. If baby does not drink it all, it can be refrigerated and served cool within two hours (<– I fail at this one too).
How long is thawed breastmilk safe to use?
Two days. To be clear, that is two days from the time the milk is completely thawed out.
This means that if you put it in the freezer at 8pm on a Saturday night and it is thawed out by 8am on Sunday morning, the clock starts at 8am on Sunday.
Can I Re-Freeze Breastmilk?
That’s a big fat NO. The risks for contamination and bacteria growth go up substantially.
Even I won’t do that. Sorry.
Helpful tips for storing breastmilk
- Store milk in small quantities. 2-4 oz is ideal to eliminate waste.
- Label milk with date, quantity, and name of child (if child will be going to daycare)
- When measuring quantity, use the ounces on the bottle as opposed to the bag. When you dump the breastmilk into the bag, it will almost always look as though there is one extra ounce. This is confusing when you are trying to track how much your baby eats later.
- When freezing in a breastmilk storage bag, lay milk on a flat surface until frozen solid.
I hope this was helpful for you! Pin it or pass it on, and hit me up in the comments if I missed anything!
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