Breast Milk Storage: The Dos and Don’ts

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Breastfeeding, exclusively pumping, or a combo of the two can be a full-time job. Case in point: A year of breastfeeding equates to a conservative estimate of 1,800 hours in a year. An essential part of the job of breastfeeding and pumping is that parents stay up-to-date on the latest guidelines for storing milk.

From storage to thawing and more, we’ll cover everything you need to know about taking care of your breast milk. You might want to bookmark this post because when you’re dealing with sleep deprivation, it can be hard to remember what day of the week it is, let alone the rules for taking care of breast milk.

After all, there is a reason many parents call breastmilk “liquid gold”—this precious liquid helps nourish your baby and helps foster a deep bond between mother and child, so it’s important to take care of it properly.

Updated Breast Milk Storage Guidelines

If you’re currently pumping, the 2022 change announced by the American Academy of Pediatrics (AAP) will likely be a welcome one. And for new and expectant mothers, it’s important to know the most up-to-date breast milk guidelines.

The updated guidelines now allow for the mixing of cold and warm pumped milk, and even recommend pooling milk pumped within 24 hours together to help even out the variability in nutrients due to pumping time or breast emptying.

The AAP guidelines previously stated that pumped milk of different temperatures should not be combined—that warm milk should be cooled in a separate container before being added to another container of already cold milk.

What’s the Best Way to Store Expressed Breast Milk?

Now that you know about the newest rules, a few other guidelines are key to understand when learning how to store breast milk.

Before handling breast milk:

  • Wash your hands with soap and water or if soap and water aren’t available, use an alcohol-based hand sanitizer that contains at least 60% alcohol.
  • Mothers using their electric breast pump should inspect the pump kit and tubing to ensure it is clean. Remember, some breast pumps parts can be put in the top rack of a dishwasher but consult the instruction manual to make sure pieces are dishwasher safe. It is not necessary to clean breast pump tubing unless it comes in contact with breast milk. However, you should discard and replace moldy tubing immediately.
  • If you’re using a shared pump, clean the pump dials, power switch, and countertop with a disinfectant wipe.

Rules for storing breast milk after expressing:

  • Use breast milk storage bags or clean, food-grade containers to store expressed breast milk. (Keep reading for additional information on choosing a breast milk container.)
  • Freshly pumped milk can be stored:
    • 4 hours at room temp
    • 4 days in the refrigerator
    • 12 months in the freezer

What Kind of Container Should Be Used to Store Expressed Breast Milk?

You worked hard for that liquid gold, mama! Whether you’re creating a stash as you prep your return back to work or stocking up for another host of reasons, it’s important to know about breast milk storage bags or other safe ways to build your supply of frozen breastmilk. These are the recommended storage guidelines.

  • Use breast milk storage bags or clean, food-grade containers to store expressed breast milk. Make sure the containers are made of glass or plastic and have tight-fitting lids.
  • Avoid bottles with the recycle symbol number 7, which indicates that the container may be made of BPA-containing plastic.
  • Never store breast milk in disposable bottle liners or plastic bags that are not intended for storing breast milk.
  • Clearly label the breast milk with the date it was expressed and the amount of milk. To avoid wasting milk, store it in 2- and 4-oz portions.
  • Do not store breast milk in the door of the refrigerator or freezer. This will help protect the breast milk from temperature changes from the door opening and closing.
  • If you don’t think you will use freshly expressed breast milk within 4 days, freeze it right away. This will help to protect the quality of the breast milk.
  • Breast milk expands when it freezes, so you need to leave about one inch of space at the top of the container.

Can Freshly Expressed Breast Milk Be Added to Already Stored Milk?

Yes, you can mix the two as long as the stored breast milk is not frozen.

When it comes to mixing breast milk and formula, the answer isn’t as straightforward. While you can mix the two, it’s preferable to do separate feedings, starting with the expressed milk first. This is so you don’t waste breast milk if your infant or baby doesn’t finish their bottle—requiring you to discard the unused portion.

If you’re considering switching baby’s milk to formula or doing a combo of breast and formula, read our guide to switching baby’s milk.

Safe Thawing of Breast Milk

Over time, the quality of breast milk can decrease, which is why it’s recommended to thaw your oldest milk first. Following a “first in, first out” policy, there are three options to consider when you want to know how to thaw breastmilk.

  • Take breast milk from the freezer and put it in the refrigerator overnight.
  • Place a frozen bag or container in warm water.
  • Run the bag or container under lukewarm water.

Now that you have the thawed milk ready to go, follow these rules:

  • If you thaw breast milk in the refrigerator, use it within 24 hours. Start counting the 24 hours when the breast milk is completely thawed, not from the time when you took it out of the freezer.
  • Once breast milk is brought to room temperature or warmed, use it within 2 hours.
  • You cannot refreeze breast milk after it has thawed.

Remember, you never want to microwave frozen breast milk. We know it’s tempting to get that milk ready ASAP when you have a red-faced wailing baby who is ready for milk now, but the microwave can zap nutrients in the milk and create hot spots, which might burn baby’s mouth.

Why Does My Frozen Breast Milk Look Different?

Did you know it’s normal and safe for your breast milk to appear in various colors? Yup, rainbow milk can appear slightly yellow, yellow-orange, pink, and even green. This color change is based on your diet and medications. Consult your baby’s doctor before feeding them if you’re ever worried about the quality of the milk.

It’s also normal for frozen breast milk to separate into a cream layer and a milk layer.

Now that you know about storing your breastmilk, remember that gas and colic both happen during your baby’s feeding journey but remember both Infants' Mylicon Gas Relief and Infants' Mylicon Daily Probiotic Drops are safe even for newborns. If you breastfeed, you can apply Infants’ Mylicon Probiotic Drops directly onto your nipple for your baby to suckle up while breastfeeding. (Keep in mind, you should always stick to the recommended dose of six drops per day.)

Infants’ Mylicon Gas Relief Drops can be dosed directly into baby's mouth or added to a bottle with 1oz of breastmilk or formula.`

Because feeding your little one can be complicated, we have your back with breastfeeding positions to try, feeding schedules for babies, and tips for introducing solids.


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