How to Thaw, Warm, and Use Frozen Breast Milk

Safety Guidelines for Defrosting Human Milk

Breastmilk
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If you're like many other breastfeeding moms, you may choose to collect and freeze your breast milk. It might be necessary if you have to transport or ship it, but it is more likely that you want to create a stockpile to have on hand for when you have to be away from your baby or when you decide to stop breastfeeding. When the time comes to use that frozen milk, it's important to know how to do it. So, here's a guide to safely thawing, warming, and using your frozen breast milk.

How to Safely Thaw Frozen Breast Milk

Thawing means to melt something that is frozen and turn it into a liquid. When you thaw out frozen breast milk according to the safety guidelines, it maintains more nutrients and is less likely to spoil. Here are some tips for safely thawing your breast milk:

  1. Your bags or containers of frozen breast milk should have a label with a date. Defrost the oldest bottle of breast milk first.
  2. You can defrost frozen breast milk by placing it in the refrigerator, putting it in a bowl of warm water, or holding it under warm running tap water. You should not thaw breast milk at room temperature.
  3. Do not use the microwave or place your breast milk in a pot of boiling water on the stove. The milk may get too hot, and it can spoil.
  4. Once you defrost your breast milk, you can warm it up and use it immediately, leave it out at room temperature for up to four hours, or place it in the refrigerator for up to 24 hours.

Note: These guidelines are for healthy, full-term infants and older children. If you have a premature baby or a child with a compromised immune system, talk to your healthcare provider for more information on how to collect, store, and use your breast milk.

How to Defrost Breast Milk in the Refrigerator

Thawing breast milk in the refrigerator can take approximately 12 hours, so be sure to plan ahead. You may want to place a full day's worth of frozen breast milk in the fridge each night so that it will be ready to use the next day.

To defrost frozen breast milk in the refrigerator:

  1. Remove the bag or bottle of the frozen breast from the freezer.
  2. Place it into the refrigerator.
  3. Wait until the solid frozen milk turns back into liquid form.
  4. Once the milk thaws, use it within 24 hours.
  5. Do not refreeze thawed breast milk that is left over after 24 hours.

How to Thaw Breast Milk in a Bowl of Warm Water

If you need to thaw breast milk quickly, you can use a bowl of warm (not hot) water. Thawing breast milk in a bowl of warm water takes approximately 20 minutes if you keep an eye on the water and change it as soon as it cools down. Here's how:

  1. Fill a bowl or pan with warm water. 
  2. Place the frozen container of breast milk into the water. Be sure to keep the water level below the cap of the breast milk bottle to prevent contamination.
  3. As the water cools down, empty it and replace it with more warm water.
  4. Continue to do this until the breast milk is no longer frozen.
  5. Once defrosted, place the milk in the refrigerator or continue to warm it up to feed to your child. 

How to Thaw Breast Milk Under Running Water

The fastest way to defrost breast milk is to hold it under a faucet of warm running water. Here is what you can do:

  1. Start out holding the container (or bag) under cold running water.
  2. Slowly make the temperature of the running water warmer, but do not make it hot.
  3. Keep holding the container under warm water until the milk thaws.

Warming Up Thawed Breast Milk 

You can give your baby thawed breast milk right out of the refrigerator, or you can warm it up to room temperature or body temperature. 

If you choose to warm your breast milk, you can:

  • Place it in a bowl of warm water for a few minutes.
  • Hold it under warm running water.
  • Use a bottle warmer.

But, you should not heat breast milk in the microwave, or in a pot of boiling water on the stove (see below).​ ​It's important to warm your breast milk correctly so that you don't burn your baby's mouth and throat.  

Once the milk is warm you should:

  • Gently swirl the container to mix any layers of the milk that may become separated during storage.
  • Check the temperature of the breast milk before giving it to your child. You can do this by squirting a few drops on the inside of your wrist. It should feel lukewarm or room temperature. It should not be hot or cold.

The Dangers of Using the Microwave and Stove

When thawing or warming a container or frozen milk, you should not use a microwave oven. The high heat from the microwave can destroy some of the healthy properties found in the breast milk. Microwaves can also heat in an uneven way causing hot areas within the breast milk. Hot spots in the milk can burn your baby's mouth and throat.

Using the stove to heat breast milk is not recommended, either. When you place a bag or container of breast milk in a pot of boiling water on the stove, it can overheat. Overheating can destroy the nutrients in the milk and make it dangerously hot for your child.

The Taste of Defrosted Breast Milk 

Sometimes thawed breast milk doesn't smell very good. It can also have a soapy, metallic taste. If this happens, it doesn't mean the milk is bad and you don't have to throw it away. The strange sour smell and taste are from an enzyme in the milk called lipase. Lipase naturally breaks down the fats in the milk during storage. It is still safe to give the milk to your baby, but your child may not drink it if he doesn't like the way it tastes.

How to Safely Handle Warmed Breast Milk

You can prevent your breast milk from spoiling or becoming a breeding ground for bacteria if you know how to handle it and use it safely. Here are some tips:

  • Once you warm the breast milk, you can give it to your child right away or put it in the refrigerator for up to 4 hours.
  • You should not leave warm breast milk out at room temperature. 
  • You should not refreeze it.
  • If your baby does not finish a feeding, you should throw away the leftover breast milk in the bottle.  

A Word From Verywell

Having extra breast milk stored in the freezer can give you some peace of mind. Whether it's just a few bags in case of an emergency or a whole stockpile of containers for when you return to work, it nice to know that your child can still have your breast milk even when you're not providing it fresh from the source. But, how you thaw and use your frozen breast milk is as important as how you collect and store it. By following the guidelines and tips above, you can keep your baby and your breast milk as safe and healthy as possible.

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Article Sources
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  • Lawrence, Ruth A., MD, Lawrence, Robert M., MD.  Breastfeeding a Guide For The Medical Profession Eighth Edition. Elsevier Health Sciences. 2015.
  • Riordan, J., and Wambach, K. Breastfeeding and Human Lactation Fourth Edition. Jones and Bartlett Learning. 2014.