The following are general guidelines for thawing frozen breast milk:
The oldest milk should be used first, unless recently expressed milk is recommended.
Thaw breast milk by placing the collection container in the refrigerator for several hours or overnight.
To thaw more quickly or to heat refrigerated milk, hold the container of milk under warm running water or place it in a cup, pot, bowl, or basin of warm water. Do not thaw milk in very hot water or in the microwave. This decreases some of the healthy properties of the milk. It can also create hot spots that may burn your child's mouth.
It is normal for your milk to separate during storage. You will see a layer of cream (fat) that has risen to the top. To recombine the cream with the rest of the milk, gently swirl the bottle. Avoid vigorous shaking.
Do not refreeze milk once it has been thawed. Thawed milk must be used within 24 hours.