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Is Microwaving Breast Milk a Bad Idea?

As parents, we are always busy and looking for ways to shave a few minutes off those everyday activities and make our lives a little easier. Of course, there is nothing wrong with that.

We have all at some point wondered if to save a few minutes we could heat up that breast milk in the microwave. But this is definitely not one of those time-saving parent hacks that you should use.

Can You Microwave Breast Milk?

The quick answer is no, you should never heat breast milk in a microwave. There are a few reasons why you should not heat breast milk in a microwave.

Firstly, microwaves do not heat food evenly, meaning that they can often end up with hot spots and these can potentially burn your baby.

Secondly, it is believed that heating breast milk in the microwave can damage the nutrients and antibodies in it.

Hot Spots

Almost every parent has a microwave in their kitchen, most families could not live without theirs – I know we couldn’t.

But how many times have you heated up food in the microwave thinking that it is hot all the way through only to find that it is mostly warm?

And then you have these incredible hot parts that burn the roof of your mouth – yeah it’s happened to me more than I would like to admit!

This is a hot spot and this happens because of uneven heating temperatures. And although you are thinking that you are a responsible parent and would thoroughly check that the milk was not hot, these hot spots can easily be missed.

This could potentially lead to your baby being scalded. 

The FDA states that “Heating breast milk or infant formula in the microwave is not recommended. Studies have shown that microwaves heat baby’s milk and formula unevenly. This results in “hot spots” that can scald a baby’s mouth and throat.”

Damaging Nutrients and Antibodies

Microwave heating also damages the nutrients and antibodies that are present in breast milk – this is after all what makes it your liquid gold!

The problem with heating breast milk in the microwave is that it begins to deteriorate once the milk reaches a certain temperature and this can easily happen in a microwave.

A study has shown that the nutritional and immunological values of breast milk begin to deteriorate at 104 degrees or higher. The study also went on to state that at 122 degrees Fahrenheit “the rate of the milk quality deterioration increases significantly.”

Now I know that those temperatures seem very high but they are actually not that high.

If you heated your breast milk to 104 degrees it would only be classed as lukewarm, and remember microwaves heat unevenly so you will get spots that are much hotter than others.

Heating your breast milk in a microwave is definitely not recommended but there are other safe ways to heat your breast milk without the concerns of hot spots or any deterioration occurring.

How Breast Milk Deteriorates When heated Above 104 Degrees Fahrenheit

Here are the ways in which human milk changes and deteriorates as it gets too hot:

  • Beneficial probiotic bacteria are destroyed.
  • White blood cells are destroyed, decreasing anti-infective properties.
  • Fat content decreases which are vital for infant growth and development.
  • Immunologic and anti-inflammatory compounds such as SlgA antibodies, lactoferrin protein, and lysozyme are decreased. All of these are essential to the healthy growth and development of infants.
  • Inactivation of digestive enzymes.

How To Warm Breast Milk From The Refrigerator

To warm breast milk direct from the refrigerator:

  1. Remove breast milk from the fridge.
  2. Heat water using either a kettle or microwave. Pour very warm but not boiling water in a jug or bowl.
  3. Place the sealed bag of breast milk or bottle in the bowl/jug of hot water. The milk needs to remain in a sealed container for heating.
  4. Leave the milk in warm water for 1-2 minutes until it reaches the desired temperature.
  5. With clean hands remove the heated breast milk and either pour it into a bottle or if already in a bottle, screw on the nipple.
  6. Swirl breast milk but do not shake to ensure that the fat is all mixed if it is separated.

Ensure that you check the temperature of the breast milk before offering it to your baby. You can do this by pouring a small amount on the inside of your wrist, it should feel warm but not hot.

How To Warm Breast Milk From The Freezer

To warm frozen breast milk, firstly remove the frozen breast milk from the freezer and place it in the fridge to thaw overnight.  Then follow the instructions above for heating breast milk from the refrigerator.

If you do need the milk immediately and it is frozen, you can heat the breast milk straight from the freezer using the same method you’d use to heat it from the fridge.

The only difference is that it will need to be left in the warm water for around 10-15 minutes, maybe longer.


Does microwaving breast milk destroy nutrients?

Never heat breast milk in a microwave as not only does it cause hot spots but it also destroys the essential nutrients and antibodies within it. This is due to the temperatures that the milk will be exposed to during the heating process within a microwave.

Can I warm breast milk twice?

Once you have reheated a partially used bottle of breast milk once, it is generally safe to reheat only one more time before you should discard any unused breast milk.

Can babies drink cold breast milk?

Yes, they certainly can drink cold breast milk. While breastfed babies who get their milk directly from the breast will drink it at body temperature.

Those babies that are formula-fed or are having expressed breast milk can drink the contents slightly warmed, at room temperature, or even cold straight from the fridge.

How long can breast milk stay out after being refrigerated?

Freshly pumped breast milk that has been left unrefrigerated for longer than four hours should be disposed of, regardless of whether it has been used in a feed or not.

Previously frozen milk should be used within 24 hours once thawed and refrigerated. If left on the counter, throw out after 2 hours.

The Final Thought

The bottom line is that saving those few minutes is not worth scalding your baby or damaging your precious breast milk from heating in a microwave.

There are plenty of other safe and quick ways to heat breast milk such as using hot water or you could even purchase a bottle warmer in order to heat your milk to the exact temperature that your baby loves.