Breast Milk Storage: Helpful Guidelines and Tips

If you’re breastfeeding, there are many reasons you might want to store your breast milk. For example, you might want to pump or express while you’re at work to and store your milk to give to your baby later, or there may be times when you want to put aside a few bottles of breast milk so that someone else can feed your little one later.

Read on to learn how to collect and safely store breast milk, and how to defrost and reheat breast milk that has been kept in storage.

How to Collect and Store Breast Milk

Whether you have a larger supply of breast milk and want to put some aside for later use, or if you need to go back to work while still breastfeeding and need to delegate some of the feeding duties to your partner or a babysitter, you might need to collect breast milk for storage.

Types of Breast Milk Storage Containers
Portioning the Breast Milk for Storage
Hygiene Guidelines for Pumping Breast Milk

Types of Breast Milk Storage Containers

The following are options for storing breast milk, and the recommended containers to use:

It’s best to collect freshly pumped or expressed breast milk in clean glass or plastic screw cap bottles or hard plastic storage cups with tight-fitting lids.
You can also use special breast milk storage bags that are pre-sterilized for storing breast milk.
Don’t store breast milk in disposable bottle liners or regular plastic storage bags that weren’t designed for breast milk storage.

Some baby bottles are designed so you can store breast milk in them straight after pumping.

Portioning the Breast Milk for Storage

Store the breast milk in two- to four-ounce portions, which is about the right amount for one feeding (read more on breastfeeding), in order to avoid waste.

Mark whichever storage container you’ve chosen with the date of pumping, and with your baby's name if the milk will be consumed at day care. Always use the oldest stored breast milk first, as long as it’s still within its use-by limit.

If you’re going to place the container in the freezer for storage, make sure to leave an inch of air space at the top since the liquid will expand when frozen.

Hygiene Guidelines for Pumping Breast Milk

There are some steps you can take to prevent transmitting bacteria to the breast milk and to your baby.

Before using your breast pump for the first time, make sure to sterilize all its parts, including the nipples, bottles, and any parts that come into contact with your breasts or the milk.

Sterilize by boiling the parts for 5 to 10 minutes. Check the manufacturer’s directions for sterilizing and follow the recommended boiling time in case it’s a little different.

Each time you use the pump, make sure to wash your hands thoroughly.

After every time you use the pump, make sure to wash the parts in hot, soapy water, or in the dishwasher, if the parts are dishwasher safe.

Time Guidelines for Breast Milk Storage

Freshly expressed or pumped breast milk can be stored in the following ways:

How to Defrost Frozen Breast Milk

Follow these tips for thawing breast milk stored in the freezer:

Thaw frozen milk by holding the container under cool running water. As it begins to thaw, switch to warm running water.
Or allow the frozen breast milk to thaw in the fridge—it might take about 24 hours.
Once the milk has thawed, give it to your baby within 24 hours.
Never thaw frozen milk at room temperature.
Do not refreeze thawed breast milk.

Can You Reheat Chilled Breast Milk?

Yes. Breast milk that’s been stored in the refrigerator, whether it’s been previously frozen or not, can be reheated if you would like to give your baby warm milk. But know that breast milk does not need to be given to your baby warm. It’s OK to feed your baby breast milk that’s chilled or at room temperature.

If you wish to reheat breast milk after storage in the fridge, follow these steps:

Place the bottle of breast milk in warm water. Use a pan or bowl of warm water to reheat your baby’s bottle, or use a bottle warmer.
Do not heat bottles on the stovetop or in the microwave. High temperatures can kill breast milk’s disease-fighting antibodies and can also create hot spots that could burn your baby’s mouth.
Check that the milk’s not too hot. Before feeding your baby, test the temperature of the breast milk by squirting it on the inside of your wrist to ensure it’s not too hot for your baby. It should feel warm on your wrist.
Don’t wait too long to give the breast milk. Once you’ve warmed the breast milk, it should be used within two hours.

Is Stored Breast Milk Any Different From Fresh Breast Milk?

Breast milk that’s been in storage, either in the refrigerator or thawed from the freezer, can look different from freshly expressed or pumped breast milk. It may even separate into a creamy layer and a milky layer. This is completely normal. Gently swirl the milk to mix it back together.

Thawed frozen milk may also smell or taste different due to a breakdown in the milk fats. It’s still safe for your baby, and most babies won’t notice the difference.

You can try mixing the previously chilled breast milk from storage with fresh breast milk in a 1:1 ratio. It’s best that the two milks are close in temperature when you do this.

If your baby does not finish the bottle of stored milk, the leftover breast milk can still be used within two hours. After that it should be discarded.

FAQs at a Glance

If you’ve removed breast milk from the refrigerator after a period of storage, once it reaches room temperature, it can be kept at up to 25 degrees Celsius for up to 4 hours.

For busy moms like you, expressing or pumping breastmilk and then storing it can be a lifesaver. Having breast milk in storage can make it easier to keep up with your baby’s feedings and allow you to share feeding duties with others. Using the info in this article and by giving it a try, you’ll soon get the hang of storing, thawing, and reheating breast milk and it will become a natural part of your life with your little one.

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