Can You Reheat Breast Milk? How Many Times?

Last Updated on March 27, 2023 by Jada Glover

As breastfeeding moms, we know that breast milk is precious. It is called “liquid gold” for a reason, right?

Have you seen those memes where it says not to cry over spilt milk, unless, of course, it is breast milk? There’s a reason why!

As hard working breastfeeding moms, we want to ensure we are using every last drop that we produce, but safely of course. Reheating breast milk can be done, but there are a few things to remember to protect your baby and the milk quality.

So, let’s get started answering the question: “Can you reheat breast milk?”

How Many Times Can You Reheat Unused Breast Milk? Can You Reheat It More Than Once?

Breast milk can be reheated once after it has been initially expressed by pump or hand expression. It is recommended that any leftover breast milk that has been previously warmed should be discarded after an hour of being offered to your baby.

You should avoid reheating it more than once because each time the breast milk is heated and cooled, there is a risk of bad bacterial growth in the milk. This bacteria can be harmful to your baby.

Human milk is a fresh, living food with many antioxidant, antibacterial, prebiotic, probiotic, and immune-boosting properties in addition to nutrients.

Academy of Breastfeeding Medicine, Human Milk Storage Information

Because of these amazing properties, we should try to preserve it as much as possible. Following these reheating guidelines can help you do this.

Can You Reheat Breast Milk In a Bottle From the Fridge?

Yes, you can reheat breast milk in a bottle from the fridge. But only if it is from the same day your baby drank from it. Or, if you pumped and stored it in the bottle (on a different day).

If your baby drank from that bottle already that day, it’s best to reheat the same milk bottle within that day. Your baby’s mouth bacteria could contaminate the bottle if used and stored for use on a different day.

To reheat it, simply put the bottle in a bowl of warm water or a bottle warmer. Use the breast milk within 1-2 hours.

Do not put the bottle on the stove in boiling water or in the microwave. After reheating breast milk in a bottle, you will want to toss out any unused milk or use it in a milk bath that night.

Can You Reheat Heated Breast Milk?

You can only reheat breast milk one time after you’ve initially expressed it. You want to avoid reheating more than that because heat destroys the good bacteria and the nutrients in the milk.

How To Store Breast Milk

When you are storing breast milk, choose food-safe containers like breast milk bags or small jars. These containers have tight-fitting zippers or lids so no air can get into the container. Also choose bags that are BPA-free to avoid chemicals leaching into your breast milk.

Label the milk with the date, number of ounces, and your baby’s name if going to child care. The ounces should be based on the collection container measurement rather than the bag since that measurement can vary.

Store your breast milk in the back of the refrigerator or freezer, so that the storage temperature remains constant. Do not store it on the door, where the temperature is more variable. When freezing your milk, leave an inch at the top of the bag or container as breast milk expands when it freezes.

I also want to mention that I love this freezer organization system for breast milk storage. It is a great tool if you are in need of space in your freezer. It allows you to lay the bags flat to save on space.

You also want to be sure your caregiver is practicing paced bottle feeding. This will help prevent throwing away any precious milk.

Remember, if your baby does not consume all the milk within two hours after it has been reheated once, it is best throw it away. If you do have some leftover, as long as it still smells good, you could use it in a milk bath that day or use it to make breast milk lotion or soap.

Storage When Traveling or Working

If you are traveling for work or vacation, your breast milk can be stored in an insulated cooler bag with frozen ice packs up to 24 hours. Be sure you put it in the freezer as soon as you arrive at your destination. You can even bring it with you on an airplane if need be.

Here are two cooler bags that you could use. Even if you’re not traveling a long distance, these are handy for daily use when you go to work and transport your milk back and forth.

If you don’t plan to use your freshly pumped milk within 4 days, go ahead and freeze it right away. When I was working out of the home and my son was nursing, I was pumping and storing my milk in smaller amounts (2-3 ounces). By doing this, I was able to waste less if he did not drink all the milk at one time.

How To Warm Frozen Milk

If you are thawing frozen milk to make it warm for your baby, place the sealed container in a bowl of warm water. Use the milk you thaw within 24 hours. This timer starts once it is completely thawed.

Always thaw the oldest milk first. The only exception to this is if your baby is sick or fighting an illness.

In my opinion, it’s best to give your little one the most recently expressed milk so he or she gets your antibodies. Most likely you are also fighting off whatever illness it is. This will help your baby’s body heal faster or prevent him or her from getting sick.

Keep in mind if your baby prefers cold milk or room temperature milk, you don’t have to warm it. Once frozen milk is warmed or brought to room temperature - use it within 2 hours.

You could also put frozen milk in the refrigerator the night before you plan to use it. This will allow it to thaw. You can then serve it cool from the fridge, at room temperature, or warmed in a bowl of warm water.

When warming your milk, do not microwave it or put it in a pot of boiling water. Microwaving breast milk destroys key nutrients and does not heat the milk evenly. This can lead to hot spots within the milk.

How To Prepare Milk From the Fridge

Milk from the fridge can be drank by your baby cold or left out for an hour at room temperature before drinking it. Another alternative is to warm milk from the fridge by putting the milk storage container (bag or glass jar usually) into a bowl of warm water.

If your milk is in a bottle, you could use a bottle warmer. Do not use a microwave or a pot of boiling water.

Overheating breast milk during the warming process can cause certain milk proteins to become inactive and decrease the fat content in the milk. The CDC has different guidelines that suggest you may be able to immediately mix newly expressed milk with refrigerated milk

However, the Academy of Breastfeeding Medicine (ABM) protocol states:

“Freshly expressed warm milk should not be added to already cooled or frozen milk, to prevent rewarming of the already stored milk. It is best to cool down the newly expressed milk first before adding it to older stored milk.”

This ABM guideline makes the most sense to me and this is what I suggest to my breastfeeding clients. When I was pumping with my son, I refrigerated the new milk in a separate container. I then added it to another one in the refrigerator later that day or the next day once it was cooled.

How Long Does Breast Milk Last at Room Temperature?

Breast milk will last for different times at room temperature depending on the environment it is in. Four hours is the general rule of thumb if it was just pumped.

According to the Academy of Breastfeeding Medicine protocol, for room temperatures ranging from 27C to 32C (29C= 85F), 4 hours may be a reasonable limit. For very clean expressed milk with very low bacterial counts, 6–8 hours at lower room temperatures may be reasonable.

But, it is best to refrigerate as soon as possible if your milk will not be used during that time. If your milk was previously refrigerated or frozen, it will last 1-2 hours at room temperature.

Be careful and mindful when reheating breast milk for your baby.

Breast milk is a special commodity when you’re working so hard to produce it for your baby. It is safe to reheat breast milk once.

It is best to use only the amount of milk that your baby needs for each feeding. Use the tips above to ensure you are handling, storing, and reheating your milk safely.