StorkNet interview with
Anne Smith, IBCLC
International Board Certified Lactation Consultant

Be sure to visit Anne Smith's website for more breastfeeding information and wonderful products. Also, read her articles on StorkNet.

Q's and A's:


Helen: How long can breast milk be stored and should it be stored in a bag or in a bottle RTU?

Anne: I'm assuming that "RTU" means "ready to use." Breastmilk can be safely stored in glass, hard plastic bottles, plastic freezer bags, or polyethylene milk storage bags especially designed for storing breast milk.

You may want to freeze your milk in ice cube trays. Clean the tray first with hot soapy water and air dry. Each cube is about an ounce, so you can pop out as many ounces as you want and put them into freezer bags. They are great to have on hand for snack or cereal feedings when you just need an extra ounce or two.

Whenever it is possible, give your baby fresh milk that has been refrigerated, not frozen. Freezing kills some of the live cells and antibodies in human milk, but not all of them. Since formula doesn't have any of these anti-infective properties to begin with, frozen milk is still better for him than formula. If you are planning to use the milk within eight days, refrigerate it rather than freezing it.

Because human milk is a living substance, its antibacterial properties help it stay fresh longer than formula. How long you can store it depends on the temperature.

  • Freshly expressed milk can be stored at room temperature for up to ten hours. Colostrum or milk expressed within one week of delivery can be stored for twelve hours at room temperature. However, whenever possible, milk should be placed in the refrigerator soon after expressing.
  • Fresh milk can be kept in the refrigerator for up to eight days. Store it toward the back.
  • Fresh milk can be stored in a cooler with icepacks for up to 24 hours.
  • Fresh milk can be placed in a freezer compartment inside a fridge for up to 2 weeks. (These are usually only found in older type refrigerators).
  • Fresh milk can be kept in a self-contained freezer compartment for 3-6 months, depending on how often the door is opened. Store it toward the back.
  • Fresh milk can be stored in a separate chest type deep freeze for 6-12 months.
  • Milk that has been frozen and thawed can be kept in the fridge for 24 hours. Thawed milk should not be refrozen.

With all these guidelines, remember that fresh milk which has been stored at room temperature or in a cooler before being placed in the fridge or freezer may not keep as long. That's why you should always place milk in the fridge as soon as possible after expressing it.

The guidelines on storing breastmilk have been revised over the last few years. There is still a lot of old information out there, so don't be surprised if the guidelines above tell you something different from what you have read in books or seen in a pamphlet that you picked up in your doctor's office.


Laura: I am going to be storing some breastmilk for times that I might not be at home so that my son's father might be able to offer him a bottle. I am using the new Avent Bottle... And the question that I have is how long can you store breastmilk in the refrigerator and or freezer... Thank you in advance for your help.

Anne: You'll find that there is some conflicting information out there about storing breastmilk. The official guidelines keep changing every few years, and there is still a lot of outdated information floating around.

The experts used to say that you could store milk in the fridge for 24 hours, then they said 48 hours, then 72 hours, and now they say that it will safely keep for up to 8 days. They used to think that because human milk wasn't pasteurized like cow's milk, then it would spoil faster than formula. Now we know that because of the live cells and antibodies in human milk that limit the growth of bacteria, it actually stays fresh much longer than cow's milk or formula.

Current general guidelines are this: fresh milk will keep in the fridge up to 8 days, and frozen milk will keep 3-4 months in a regular freezer compartment with a separate door, and in a chest type deep freezer, 6-12 months.

Always use fresh milk when you can, because freezing the milk will kill some of the live cells. Frozen breastmilk is still better than formula, because freezing doesn't kill all the cells, and formula doesn't have any to begin with.

You can find out lots more details about storing milk in my article "Collecting and Storing Breastmilk."

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