Breast milk storage: Do's and don'ts

Breast milk storage can be confusing. Follow these practical tips on choosing containers, freezing breast milk, thawing breast milk and more. By Mayo Clinic Staff

If you're breast-feeding your baby and going back to work or looking for more flexibility, you're probably considering using a breast pump. Once you start pumping, it's important to know how to safely and properly store your expressed breast milk. Consider these do's and don'ts for breast milk storage.

What kind of container should I use to store expressed breast milk?

Before expressing or handling breast milk, wash your hands with soap and water. Then store the expressed milk in a clean, capped glass or hard plastic container. You can also use special plastic bags designed for milk collection and storage. Keep in mind that breast milk storage bags aren't generally recommended for long-term storage because they might spill, leak and become contaminated more easily than hard-sided containers. For extra protection, you can place the bags in a hard plastic food storage container with a tightly sealed lid. Also, certain components of breast milk might adhere to the soft plastic bags during long-term breast milk storage, which could deprive your baby of essential nutrients.

Don't store breast milk in disposable bottle liners or plastic bags designed for general household use.

What's the best way to store expressed breast milk?

Using waterproof labels and ink, label each container with the date you expressed the breast milk. If you're storing expressed milk at your baby's child care facility, add your baby's name to the label. Place the containers in the back of the refrigerator or freezer, where the temperature is the coolest. If you don't have access to a refrigerator or freezer, store the milk in a cooler or insulated bag until you can transfer the milk to the refrigerator or freezer.

To minimize waste, fill individual containers with the amount of milk your baby will need for one feeding. You might start with 2 to 4 ounces (59 to 118 milliliters), and then adjust as needed. Also consider storing smaller portions — 1 to 2 ounces (30 to 59 milliliters) — for unexpected situations or delays in regular feedings. Keep in mind that breast milk expands as it freezes, so don't fill containers to the brim.

Can I add freshly expressed breast milk to already stored milk?

You can add freshly expressed breast milk to refrigerated or frozen milk you expressed earlier in the same day. However, be sure to thoroughly cool the freshly expressed breast milk in the refrigerator or a cooler with ice packs before adding it to previously chilled or frozen milk. Don't add warm breast milk to frozen breast milk because it will cause the frozen milk to partially thaw. Keep milk expressed on different days in separate containers.

Apr. 06, 2012 See more In-depth