How to Thaw, Warm, and Use Breast Milk

Are you struggling to remember exactly how to store breast milk? Not only how long it can stay in the fridge or freezer… But what about thawing breast milk? Or maybe you’ve wondered, once breast milk is heated can it be refrigerated?

Remembering everything about breast milk storage guidelines can get a bit tricky until you get the hang of it. In this post, we’re going to go through exactly how to thaw, warm, and use breast milk!

Warming Up Breast Milk

Here are the ways you can safely warm up your breast milk – in a bowl of warm water, by holding it under warm running water, or with a bottle warmer.

This can be done with fresh breast milk or defrosted frozen breast milk.

You want the milk to be lukewarm or at room temperature, not too hot. You can test this by putting a few drops of milk on the inside of your wrist. This is more sensitive skin that will be able to tell a temperature difference well. If it doesn’t feel hot or cold, but like your body temperature, then you’re good to feed your baby.

Many parents wonder once breast milk is heated, can it be refrigerated? And the answer to that sadly is no (you cannot refreeze it either). Any heated breast milk or leftover milk that your baby did not finish from their bottle will have to be discarded after 2 hours. This is due to the risk of bacterial growth.

So make sure that you don’t heat your baby’s bottle too far in advance before they are hungry!

Tip: Swirl the bottle after heating to remix the breast milk fats that may have separated.

Thawing Frozen Breast Milk

There are a few different methods you can use that are safe and effective to thaw frozen breast milk. These methods include – thawing breast milk in the refrigerator, under warm running water, in a bowl of warm water, or in a bottle warmer.

The storage guidelines (how long the breast milk is good for) change depending upon how you thaw the breast milk. We’ll go over that in detail in each section.

If you have a breast milk stash, choose the oldest milk to thaw. This prevents milk from reaching its expiration date before you can use it. So be sure to label the date on all of your breast milk when storing!

You CANNOT use a microwave oven or boiling water to thaw your breast milk. These methods can break down the good nutrients and health properties in your breast milk. And also create hot spots within the breast milk which is very unsafe and can scald your baby’s mouth.

Thawing Breast Milk in the Refrigerator

If you plan out your baby’s bottles in advance, thawing breast milk in the refrigerator is a great option. Once the breast milk is defrosted, you have 24 hours to use the breast milk.

It can take quite some time for the breast milk to completely defrost in the fridge. About 12-16 hours depending upon how much milk is in each bag. So make sure if you choose this method that you plan ahead.

The great part is you can now use that milk for the next 24 hours to create breast milk bottles throughout the day. And then warm them as you need them.

Thawing Breast Milk Under Warm Running Water

Placing breast milk under warm running water is a quick and easy way to thaw frozen breast milk. You can do this with any container of milk, bottle, or storage bag. Make sure the water is warm, not hot, and hold it under until the milk thaws.

You can also continue to warm your baby’s bottle this way. Just be sure to test the temperature before giving it to your baby. Once the milk has reached room temperature or warm, use it within 2 hours.

Thawing Breast Milk in a Bowl of Warm Water

Thawing breast milk in a bowl of warm water is an easy way to quickly defrost breast milk. Be sure to use warm and not hot water. And keep an eye on the water and switch it out if it starts to become cold to speed up the process of defrosting.

You can also just continue to warm your breast milk for your baby’s bottle this way. Once the milk has reached room temperature or warm, it has to be used within 2 hours.

Thawing Breast Milk in a Bottle Warmer

can you save breast milk after it has been heated

Some bottle warmers have the option to thaw breast milk, rather than just warm it. Be sure to check which bottle warmer you have, and also what kind of storage containers they can defrost. Some can only defrost bottles while others can do bottles and plastic bags.

Follow your specific bottle warmers instructions and guidelines for defrosting your breast milk. If the bottle warmer doesn’t specify that you can place the milk back in the refrigerator, then use the breast milk after defrosting within 2 hours.

Guidelines for Storing Breast Milk

The Centers for Disease Control and Prevention (CDC) recommends after expressing breast milk it can be stored:

for 4 hours at room temperature
for up to 4 days in the refrigerator
for 6-12 months in the freezer

The CDC also recommends storing your breast milk at the back of the freezer or the back of the refrigerator. Not on the side doors as the temperature can be inconsistent there.

If you’d like a FREE printable with the most up-to-date breast milk storage guidelines, you can sign up right here! Keep it on your fridge for an easy and frequent reminder of how to safely store and use your breast milk!

Storage Tips

If you don’t think you will use the breast milk within 4 days after expressing it, freeze it right away! This keeps your breast milk at the best quality possible.

Freeze your breast milk in smaller amounts, like 3-4 ounces. I usually recommend freezing however many ounces your baby takes in a bottle per bag or storage container. However, if you have an oversupply, you may need to store in larger amounts to save space.

A really helpful mom hack is to use a silicone freezer tray that stores in one-ounce increments. Freeze a couple of one-ounce cubes and save them in the freezer. Then, next time your baby is hitting a growth spurt or still hungry after their bottle, you can just pop one to two ounces in a bottle and warm it up. Instead of defrosting a whole bag and wasting ounces that they probably wouldn’t take within 2 hours.

Frequently Asked Questions

Once breast milk is heated can it be refrigerated?

No, unfortunately not! Once breast milk is brought to room temperature or heated, you cannot refreeze it and it cannot be refrigerated. It must be discarded after 2 hours of being brought to room temperature or warmed.

How long can refrigerated breast milk be left out at room temperature?

Refrigerated milk or frozen milk that has been thawed can sit out at room temperature for up to 2 hours before it has to be discarded.

If it’s freshly expressed or pumped breast milk, it can be left at room temperature for 4 hours.

My baby didn’t finish the bottle of breast milk, can I reuse it?

If your baby didn’t finish their bottle, you can keep it out at room temperature on the counter for up to 2 hours after you warmed the bottle. A breast milk bottle is good for 2 hours after a feeding.

Sometimes babies don’t want their whole bottle in that feeding session, but an hour later will be crying because they’re hungry again. I always recommend keeping that bottle out for the two hours just in case this happens!

After the 2 hours are up, you cannot reuse the bottle anymore.

How to warm breast milk from the fridge?

You can use any of the methods discussed above – running under warm water, in a bowl of warm water, or in a bottle warmer.

I hope this post was helpful for you in becoming a pro at how to use and store your breast milk! You can always refer back to my free printable anytime you’re unsure. If you have any extra questions, be sure to leave them below so I can help you.

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How to Thaw, Warm, and Use Breast Milk

Warming Up Breast Milk