How Long Does Breast Milk Last After Warming?

By Cindy Puppos | March 20, 2023

When you warm breast milk, it's important to understand how long it lasts. Here's what you need to know about how long breast milk lasts after warming.

Did you know that the U.S. Dietary Guidelines for Americans recommends that infants be exclusively breastfed for about the first six months? They also recommend continuing breastfeeding while introducing complementary foods for one year and older.

You might have several questions if you're breastfeeding or about to begin. For example, how long does breast milk last after warming it? 

While the answers to these questions might seem hard to find, they don't have to be. Read this guide to find out how long breast milk lasts after warming it today.

How Long Does Warm Breast Milk Last?

If the breast milk is at room temperature after being frozen, use it within two hours.

For milk that is in the refrigerator and never brought to room temperature, it will last for about 24 hours.

Never refreeze breast milk. That makes milk storage even more important.

Use a breast pump to get your breast milk into a feeding bottle, or hand express the milk. You can place it into storage bags for future use. 

Keep It Airtight

Whether you use a milk bag or bottle, keep it properly sealed. Double-check that you have been keeping it airtight.

Seal off their bottle to avoid contamination from the environment. It will also prevent water penetration. For storage bags, check that the zip lock is in place.

Room Temperature Warming

If you plan on keeping your breastmilk at room temperature, you could store it for up to four hours. Ensure you follow all cleaning and sanitization requirements for the pump. You could have safe milk storage for up to six hours in clean areas.

In a fridge, storage allows you to keep it for three to five days. The fridge needs to stay at 39 degrees Fahrenheit or cooler.

Freezer Breast Milk

Freezing breast milk needs to be 0 degrees Fahrenheit or cooler. It can last for six to nine months. This is if it is kept in sanitary and clean conditions.

Storage Tips

Use an insulated cooler bag with ice packs if you are traveling. It will last about a day like this. Once you arrive, use your breast milk right away, freeze, or place it in the fridge.

If you aren't sure you'll use the breast milk in a few days, it's best to freeze it. Use labels on containers if your child is heading to daycare.

The label should include their name and the date. Keep an inch of space in the storage container since it could expand while freezing. Avoid using the fridge door for storing the breast milk since the temperature could vary.

Can You Reheat a Bottle?

Yes, if it is within two hours. It's up to you whether you'd like to leave it at room temperature or rewarm it.

For food, refrigeration does slow down bacterial growth. Although, many moms rewarm without a problem.

Whereas with previously frozen milk, you can't refreeze it. You'll need to use it within a day once it finishes thawing.

Can You Let the Bottle Become Room Temperature?

Yes. It is up to you whether you'd like to use a bottle warmer or let it warm up at room temperature. After storing it in the freezer or refrigerator and warming it, you will need to use it within two hours.

Storage Guidelines-Freshly Expressed Milk

For ice packs/an insulated cooler, it'll store for about 24 hours. Ideally, it'll store for three to four hours at room temperature. For warm rooms, it could also last for three to four hours.

For frozen milk, never refreeze it. The freezer compartment in a fridge will last about two weeks.

For a deep freeze, it could last about a year. For self-contained freezers, it can store for about six months.

Avoiding Waste

To avoid waste, keep milk in one to four-ounce portions. Keep it in a dated label.

It could be combined in one container if it is from different days/sessions. Don't add warm milk to a container that has been frozen or refrigerated.

Cool it first before combining it. You will know if breast milk isn't good anymore. It'll taste sour or smell bad.

How to Warm Milk

First, heat water in a cup and place frozen milk to warm it. You could also use a bottle warmer. Never microwave human milk or heat it on the stove.

Once the cream rises to the top, swirl the milk around. Never mix it before checking the temperature. If the baby does not finish the milk, you can save it for the next feeding in one to two hours.

Checking the Temperature

Place 3 drops on the back of your hands or wrist. This is because your skin's tolerance won't be the same as your baby's.

How to Tell the Breast Milk Has Expired

If it chunks up and does not mix again, it is expired. Next, check the scent.

If it has a foul odor, it's expired. Lastly, you could see if there's a musty/sour taste.

How Long Breast Milk Lasts Out

This guide provides an overview of breast milk safety for you and your baby. Do plenty of research and write down these instructions to keep them handy.

Are you ready to get started with your very first breast pump? Did you know that insurance could pay for it?

Set up an account or call us at (888) 977-2229 to get started. We verify your insurance, work with your doctor to obtain a prescription, and file your breast pump claim.

Cindy Puppos

About the Author

Cindy Puppos is 1 Natural Way's Customer Service Manager, so she has a good idea of all the different and wonderful questions that moms have for her team. Thankfully, as the mother of two boys (who are now grown!) and a veteran of the company and breastfeeding, Cindy is always knowledgeable about breastfeeding, pumping and all the latest and greatest pumps!

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