Is there a limit to how many times you can reheat a bottle of breast milk?

By Published On: January 29th, 2010
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It’s usually best when feeding from the bottle to start with a small amount of human milk. This way you don’t have to worry about leftover milk from the feeding. You can always warm more expressed breast milk and continue the feeding if your little one is still hungry. If you end up with milk leftover at the end of a feeding, it doesn’t have to go to waste. The general recommendation is a bottle that has been used for a feeding is safe to be saved and used for the next feeding. After that any remaining warm breast milk should be discarded.

Storing Breast Milk

For storage guidelines, you should always make sure to put any unused breast milk in the fridge as soon as possible once baby has stopped feeding. If you let the thawed breast milk milk sit around too long, bacteria can start forming due to saliva from baby’s mouth that gets into the milk during feeding. Once a bottle of breast milk is refrigerating, the fat will begin to separate from the milk, so be sure to mix the milk gently before feeding again. (PS: Worried about over-agitating your pumped milk by shaking the bottle? Good news! There’s no scientific evidence to support the claim that shaking breast milk takes away from its nutritional value or antibodies, or that swirling is better.)

Reheating Expressed Breast Milk

To properly reheat the milk, warm water on the stove and place the container of milk in the hot water (but not boiling); never reheat breast milk in the microwave. According to the Academy of Breastfeeding Medicine, microwaving milk (this includes room temperature and frozen breast milk) can heat unevenly and create hot spots within the milk. A bottle warmer can give you more peace of mind for thawing and warming to a proper temperature if you’re unsure, though it’s not required.

Lastly, just use common sense—like regular milk, if breast milk has gone bad you can tell, and it’s always better to err on the side of caution when it comes to the safety of your milk supply. Just remember that each time you reheat a bottle of breast milk, it will lose some of its immunologic properties, so whenever possible, try to make a bottle (whether stored or fresh from your breast pump) with only the amount that your baby can eat.

Remember that it’s a wonderful gift to breastfeed and it offers a bevy of benefits for continuing to nurture a healthy baby. For more information on reheating, breast milk storage, or to connect with lactation experts in your area, visit La Leche League or The Lactation Network for additional resources.

-By Molly Petersen, Certified Lactation Consultant at Lansinoh