source : http://www.chp.edu/CHP/P02682
Thawing Breast Milk
General guidelines for thawing frozen breast milk:
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 breast milk at room temperature, in very hot water, or in the microwave. Microwaving can create hot spots, plus this method of heating or heating in very hot water may decrease the amount of certain anti-infective properties in the milk.
Your milk separates during storage and the cream (fat) rises to the top, because breast milk is not homogenized. Gently swirl, or rotate, the collection bottle of milk to mix it together. Avoid vigorous shaking.
Do not refreeze milk once it has been thawed. Thawed milk must be used within 24 hours. (You can use it within 24 to 48 hours once home.)