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Breast Milk Storage

Guidelines for the safe storage and preparation of human breast milk.


  • Store milk in approved breast milk storage bags or bottles, avoiding any plastics that contain bisphenol A (BPA)
  • Store in volumes of 2-4 ounces in order to limit potential milk waste.
  • Leave additional space at the top of the bag or bottle if freezing, as the milk may expand when frozen.
  • Label each bag or bottle with the date and time, as well as your baby’s name if bringing to a childcare facility.
  • Do not add fresh milk to refrigerated or frozen milk for storing at the risk of warming the previously cooled milk.
  • When storing in the refrigerator, store near the back away from the door in order to prevent any unwanted warming of milk.
  • If not planning to use within 3 days, consider placing directly into the freezer.


  • Thaw the oldest milk first.
  • Milk may be thawed in the refrigerator by simply placing the frozen milk into the refrigerator. This may be done overnight in preparation for the following day.
  • Milk may be thawed by placing the frozen milk on the counter at room temperature.
  • Frozen milk may be thawed more quickly by placing the frozen bag or bottle directly into a bowl of warm water, or by placing it under running warm water.
  • Thawed milk should never be refrozen.


  • Milk may safely be administered to your baby cold, at room temperature, or warmed. Though it will be most comfortable for you baby to be warmed to a temperature in between room temperature and body temperature.
  • To warm, place the milk in its sealed container into a bowl of warm water or run under warm water for a few minutes. You may also use a bottle warmer. Always test a few drops on your inner wrist before feeding it to your baby.
  • Never microwave milk or heat directly on the stove. Microwaving does not equally distribute heat which may result is some of the milk being too hot for your baby. Microwaving also can change the composition of important proteins in your milk.
  • If your baby does not finish the bottle of warmed milk, it may be kept out at room temperature and re-fed within one hour, then should be discarded.