How to Properly Warm Breast Milk

For the first months of life, breast milk is the best and only milk your tiny human needs to meet his/her nutritional requirements. Breast milk that has been stored in the refrigerator or frozen will most likely need to be warmed for your baby.

However, some babies will actually not require warming, so it’s best to try feeding your baby the refrigerated milk before warming and he/she may like it cool …and if so, you may be one of the fortunate ones who will not need to warm the breast milk before feeding!  

Here are some very important points on how to warm breast milk:

1. Do not microwave breast milk to warm the breast milk because microwaving can destroy the beneficial properties of the breast milk. The microwave will warm breast milk unevenly and can overheat the breast milk and can create “hot spots” in the milk. Bottles and bags of breast milk can explode in the microwave if cooked too long.
   
   
2. The best tried and true technique for testing the temperature of the breast milk is to drop some of the warmed breast milk on your wrist after heating.
   
   
3. To warm the breast milk, if the breast milk is still frozen, run the bag or bottle under cool water until thawed and then gradually increase the temperature of the water until the warmed breast milk reaches the right temperature. Bring the temperature of the water up slowly. This warming process will take the most time.
   
   
4. Do not warm the breast milk in a pot on the stove.
   
   
5. If time permits, its best to allow frozen breast milk to thaw completely in the refrigerator. Take the milk out of the freezer the night before, and remember the first in, first out rule. After thawing in the refrigerator, it is much easier to warm the breast milk by simply holding the bag or bottle under warm water for a few minutes.
   
   
6. Do not thaw breast milk by letting the bags or bottles sit out if room temperature is below 77 degrees, per Academy of Breastfeeding Medicine protocol, 2017.
   
   
7. Note that frozen breast milk may have separated into two layers; the cream will rise to the top when frozen. So after warming the breast milk, swirl the bag or bottle very gently to mix before feeding your baby. Shaking the warmed breast milk too much can damage the proteins.
   
   
8. There is some evidence from studies that indicate that thawed milk can be refrozen. However, the CDC does not recommend refreezing milk.
   
   
9. If you are traveling with expressed milk, see our tips for how to safely heat breastmilk in an airport or when driving long distances.