Skip to main content


URMC / Encyclopedia / Content

Storing Your Breastmilk

Practical considerations when storing your breastmilk

Hard plastic containers or breastmilk storage bags are the best storage containers for human milk, especially if it is to be frozen and stored for weeks or months. Avoid using regular disposable bags (such as kitchen bags or those created for bottle feeding) as freezing may cause leaking and breakdown. If using bags, squeeze the air from the top before sealing tightly. Place storage bags upright in another container or the milk may leak. However, if the double zipper seal on the breastmilk storage bag is reliable, freezing the milk flat will result in faster thawing.

You may combine milk pumped from both breasts into a single container by carefully pouring the milk from one container into the other. Store only 2 to 4 ounces per container. It is easier to thaw a second container of milk than to watch your valuable milk be poured down the drain because it was not used. Label each collection container with the date and any medicines you have taken. It is best not to combine milk from different pumping sessions. 

Health considerations when storing your breastmilk

The following guidelines are for healthy, term infants. Storage guidelines may be different for premature or high-risk infants. Talk with your baby's healthcare provider for specific instructions.

"Fresh" breastmilk contains the most active anti-infective properties, followed by refrigerated, and then frozen breastmilk.

Unrefrigerated fresh milk may be left at room temperature of 77°F (25°C), but it must be used within 8 hours.

It probably is better to refrigerate fresh milk when it is not going to be used within 60 minutes. The refrigerator should be at a temperature of 32°F to 39°F (0°C to 4°C). Do not freeze milk for a high-risk baby when that milk has been refrigerated for more than 24 to 48 hours.

If refrigerated milk will not be given within one week, freeze it for later use. Milk can be frozen for approximately:

  • Up to 2 weeks if the freezer compartment is within the refrigerator. (You must open the refrigerator door to reach the freezer with this model.)

  • Three to 6 months in a freezer that is part of a refrigerator unit but has a separate door.

  • Six to 12 months in a separate, -4°F (-20°C) "deep" freezer.

To keep milk cool when a refrigerator is not immediately available, or to transport refrigerated or frozen milk, place it in an insulated bag or cooler with a frozen cold pack. It should be moved to (or back to) a refrigerator or freezer within 24 hours. 

Medical Reviewers:

  • Dozier, Tennille, RN, BSN, RDMS
  • Rosen-Carole, Casey, MD, MPH