How can breastmilk be thawed?

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Breastmilk can be thawed in the refrigerator, in a container of (warm) water or under running (warm) water.1

Please find proper thawing instructions at Woman’shealth and the CDC.

Please note that it is not advisable to defrost breastmilk in the microwave. As per CDC guidelines:

  • “Microwave ovens do not heat liquids evenly. Uneven heating could easily scald a baby or damage the milk.
  • Bottles may explode if left in the microwave too long.
  • Excess heat can destroy the nutrient quality of the expressed milk.”

Microwave heating can also cause a significant decrease in activity of anti-infective properties. This research concludes that “Microwaving appears to be contraindicated at high temperatures, and questions regarding its safety exist even at low temperatures.”

Thawed milk can be kept in the refrigerator for 24 hours. According to the USDA, “Once food is thawed in the refrigerator, it is safe to refreeze it without cooking.” In this protocol, Dr. Anne Eglash, M.D. writes: “At this time, there is little information on refreezing of thawed [fresh –ed.] human milk. Bacterial growth and loss of antibacterial activity in thawed milk will vary depending on the technique of milk thawing, duration of the thaw, and the amount of bacteria in the milk at the time of expression. At this time no recommendations can be made on the refreezing of thawed human milk.”

Please see ‘How can breastmilk be reused’ for further information.

Next: How can breastmilk be pasteurized at home?


  1. Please note: Some parents have experienced leakage with their storage bags when thawing them. Thawing storage bags of breastmilk is best done by handling them with clean hands, wiping the outside of the bag clean, and putting them in a bowl to collect any potentially leaked breastmilk. []

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