Why should I store breast milk?

If you’re expressing or pumping breast milk, it’s good to know how to store it. Storing your milk allows you to have it ready for your baby whenever you need it. It’s important to store milk properly so that it’s fresh and maintains its nutritional and anti-infective qualities.

Breast milk can be stored in the fridge, freezer or even at room temperature. Each method of storing your milk has timeframes attached to it and it’s important to know the guidelines for each before storing your milk.

What containers can I use to store breast milk?

There are several different types of containers you can use to store expressed breast milk. It’s important to plan where your containers will be stored (fridge or freezer) and how long you plan to keep them in storage when you pick your container.

Breast milk should be stored in small amounts (2 to 4 ounces) to decrease wasting milk in the following types of containers:

  • Glass containers: This option is the preferred choice for freezing milk because the components of milk are better preserved in glass. However, because glass can break, it may not be as convenient as other options. Also, some child care centers may not accept glass containers.
  • Hard-sided clear plastic containers: For many, these are a good alternative to glass containers. Be sure to store breast milk in clear plastic bottles. Never use bottles that may have BPA in them (avoid bottles with the recycle symbol 7).
  • Freezer bags specially designed for breast milk storage: Storage bags are another choice for freezing your breast milk. It’s very important to purchase bags that are specifically designed for freezing your expressed breast milk. Of the three storage options, this one is most likely to leak. Also, if the bag is warmed in water, your milk could become contaminated if the water level goes over the seal at the top of the bag. If you pick breast milk freezer bags for storage, some tips to ensure safety include:
    • Use a double bag if you’re using a thinner storage bag.
    • Place all storage bags that contain breast milk inside a hard plastic storage container with a lid within the freezer.
    • Never using ordinary plastic storage bags or bottle liners to store your breast milk. Only use specially designed nursery bags for storing your milk.
    • Warm the bag in water that doesn’t go over the top of the bag. This helps prevent water seeping into the bag. If the water you use for warming your milk looks cloudy, there’s probably been a leak and you need to throw out that bag of milk.

No matter which option you choose, it’s important to make sure that the container has a tight seal. Check the lid or seam (if you’re using a freezer bag) for a tight seal before storing it.

How long can breast milk stay in the fridge?

After you express breast milk, you can store it in the refrigerator for up to eight days, but it's best to use it in four days. Your fridge should be around 32 to 39 degrees F for proper storage of the milk. It’s a good idea to label your milk and use up the oldest container first and then work your way through to the newest milk.

How long can breast milk stay at room temperature?

The amount of time you can keep breast milk out at room temperature can vary depending on how warm the room is. If the room is 77 degrees F or below, breast milk is best used within four hours but may be safe for up to eight hours if it is expressed in a sanitary manner. If your baby doesn’t finish the full amount in one feeding, you can use it again within two hours without refrigerating it.

How long can I keep breast milk in the freezer?

Freezing your milk allows you to keep it for longer periods of time. However, it’s important to think about what type of freezer you’re using, as well as where in your freezer you will store your milk. If you have a freezer compartment in a fridge with a separate freezer door, you can store frozen milk for three to four months. If your freezer door is contained within your refrigerator space, you can only keep frozen milk for up to two weeks. When you use a separate deep freezer, you can store expressed breast milk for six months or longer.

One thing to keep in mind is where you place the milk containers within your freezer. Don't store the breast milk in the freezer door rack. Milk stored in the door is exposed to wide temperature changes when you open and close the freezer door. It’s best to place milk toward the back, away from the door to avoid these temperature changes.

How much milk should I store to meet my baby’s needs?

Consider storing 2 to 4 ounces of milk per container. This is the average amount of milk consumed in a single feeding. You may also want to store some milk in smaller 1 to 2 ounce increments. This amount is particularly good for babies less than 6 weeks old and can be used as a small snack at any time for babies of any age. Milk that’s stored in smaller sizes can be warmed quickly and may cut down the amount that would otherwise go unused and have to be thrown away.

What milk should I use first?

When you’re storing your milk, always label it with the date it was expressed. You should use the oldest dated milk first. Clearly labeling all expressed milk will allow you to organize and keep track of what you have it your freezer. Labeling is also important if you’re taking milk to your baby’s child care center. Make sure to take milk that has the date it was expressed and your baby’s name clearly visible on the container to avoid any confusion at the center.

What should my frozen milk look like?

Don’t be alarmed if your milk looks unusual when it’s frozen. It’s normal for stored milk to separate into a cream and a milk layer. It’s also normal and safe for your breast milk to appear in a range of colors. These colors can include:

  • Slightly yellow.
  • Yellow-orange.
  • Pink.
  • Green.

The color of your breast milk can actually change based on what you eat, drink and what medications you take. If you’re ever concerned about the color of your stored milk, reach out to your healthcare provider for their advice before feeding that container to your baby.

How do I thaw and warm milk?

Start thawing or heating the milk by running it under warm running water for a few minutes. You can also swirl the container in a bowl of warm water. Once it’s warmed up, test the milk’s temperature by spilling a droplet or two on your wrist. If the milk is slightly warm (and not hot), it’s okay to give to your baby. If it’s hot to the touch, wait for it to cool down before giving it to your baby. Babies can also drink cold or room temperature milk but they may not prefer it.

Don't use a microwave to heat breast milk. A microwave doesn’t heat breast milk evenly and can scald your baby. This method for heating up milk can also destroy important proteins and vitamins in the milk. In some cases, it can also cause the bottle to explode if it’s heated for too long.

You also shouldn’t warm a container or bag of milk directly on the stove. Instead, heat the pan of water on the stove, remove the pan from the stove, and then place the container into the warm water. High heating may lower some nutrient levels in the milk. Don't bring the temperature of the milk to a high heat or boiling point.

How long can thawed milk be safely used?

If you’ve frozen and then thawed breast milk, it can be refrigerated for up to 24 hours for later use. You shouldn’t refreeze the milk. There’s very little evidence to support if stored, warmed and partially consumed milk can continue to be used. It appears safe to continue feeding previously used milk up to one to two hours after it has been prepared. After that, any unused milk should be discarded.

Are there any other tips for storing breast milk?

A few other things to keep in mind when you store your breast milk include:

  • Wash your hands before expressing or handling your milk.
  • Use containers that have been washed in hot, soapy water and rinsed.
  • Freeze breast milk if it won’t be used within 24 hours.
  • Combine cooled milk with other cooled or frozen milk as long as the quantity of the cooled milk is small enough that it doesn’t thaw a frozen batch.
  • Date the milk before storing it.

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