If you are pumping breast milk to feed to your baby, it's important to know that storage guidelines are very different than what you may hear from friends about formula. Breast milk is more than simply a food or beverage…it is a living organism. Unlike formula, breast milk has natural anti-bacterial properties (according to La Leche League, some studies show less bacterial activity in refrigerated breast milk after 8 days than on the day of expression!).
Pumped breast milk can be fed to a baby immediately after pumping (for example, for mothers pumping exclusively or dealing with latch issues), after short-term refrigeration or after long-term freezing. Each way of storing milk has different guidelines for safe storage and use.
Here's some basic guidelines for breast milk storage:
Freshly pumped milk, unlike cow's milk or formula, can be pumped and stored at room temperature (not *too* warm a room) for about 4-8 hours. If you pop it in a closed cooler bag in direct continuous contact with frozen ice blocks, that increases to about 24 hours (keep that bag closed except when changing out the ice blocks, which probably won't make it 24 hours).
There's varying ranges given by different agencies for refrigerated milk, but most seem to focus down on a storage range of 4-7 days (some say up to 10) for freshly pumped milk that goes right into the refrigerator. Don't keep the milk in the door – keep it towards the back of the fridge.
It's important to note that it is normal for milk stored in the refrigerator to separate with a cream layer on top. This is normal (cow's milk does this too if not homogenized!). Simply swirl the milk gently to remix.
Milk should be frozen as quickly as possible after being expressed. However, if you are pumping small amounts and combining before freezing, collect milk in the refrigerator in an appropriate clean bottle, or build up several bottles, then combine and freeze at once. Do not add warm milk to frozen milk.
In a standard freezer (freezer/fridge combination with separate doors) the general consensus is that milk can remain frozen for 3-6 months, or possibly up to 12. Milk should be stored in bags or containers intended for breast milk freezer storage (see my article on Breast Milk Pumping and Storage Basics for more details through related links below). In an older refrigerator with an internal freezer, the storage time is less – three months is the common recommendation. In a dedicated deep freezer, it's longer, more like 12 months. After thawing, frozen milk can be refrigerated for 24 hours. Thawed milk should not be refrozen.
For more information on pumping, storing and using stored breast milk, also see my articles "Breast Milk Pumping and Storage Basics" and "Using Stored Breast Milk – Guidelines" through the Related Links section below.
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