Breast Milk Freezer Storage: How to Rotate Your Freezer Stash

If you are an exclusive pumper that has enough supply to pump extra milk, it’s a good idea to start freezing your milk in breast milk bags and building up some breast milk freezer storage. A freezer stash can be great for peace of mind: it makes it easier not to cry over spilled breast milk, it’s there if you experience a drop in supply, and it helps you not throttle your husband when he accidentally leaves the daycare bottles out overnight on the counter. (Not that that has happened to me.)

Breast milk doesn’t last in the freezer indefinitely, though. Here is how to help make sure you don’t waste any milk by rotating your freezer stash.

How long can breast milk be kept in the freezer?

The length of time that frozen breast milk will be good in the freezer depends on the type of freezer that you are using (more information is available here):

• In a freezer compartment (like in a mini-fridge): 2 weeks
• In a separate freezer (usually attached to a refrigerator): 3-6 months
• In a deep freezer (infrequently opened): 6-12 months

Therefore, depending on the type of freezer you have and how old your baby is when you start freezing milk, your milk might not last as long as you need it to. For example, if you start freezing milk in your baby’s first month in a “normal” freezer (attached to a refrigerator), that milk should be used by the time your baby is 7 months old. If you plan on pumping past that point, you need to have a system in place to use the old milk before it goes bad.

This is where rotating your freezer stash come in. Rotating your freezer stash means using the oldest milk that you have on hand to feed your baby while the newer milk that you pump goes into the freezer to replace it.

How consistent you need to be about rotating your freezer stash depends on what kind of freezer you have. If you only have a freezer compartment, you’ll need to be constantly rotating what you’ve frozen. If you have a deep freeze that you rarely open, milk rotation is less of a concern since your milk will likely still be good as long as your baby needs it (i.e., until they turn a year old). With a freezer attached to a fridge, you’ll need to rotate on a somewhat regular basis.

How should I rotate my milk?

There are a couple of different approaches that you can take to rotating your freezer stash. Here are the two that I used:

• Pick a day each week where you baby only eats the oldest breast milk that you have frozen, while all the milk that you pump that day goes into the freezer. So, for example, every Monday is frozen milk day. This is a pretty simple way to do it – you can even do all of the defrosting for Monday’s bottles at once on Sunday night and all of the freezing of Monday’s pumped milk on Tuesday mornings.
• Every day, give your baby one frozen milk bottle (say, their pre-bedtime bottle), while freezing the milk that you pumped for that feeding. One advantage of this method is that your baby still gets fresh milk, with all of its antibodies, every day. The main disadvantage is that you have to deal with defrosting and freezing milk every day; fresh milk is easier to deal with.

Is there anything I can use to make dealing with my breast milk freezer storage easier?

You definitely want to make sure that you good breast milk bags. (I recommend the Lansinoh ones and have had the fewest leaks with them.)

In order to know what milk is the oldest, you’ll want to make sure that you label the breast milk bag with the date (if you’ve combined milk from more than one day in the bag, use the earlier date). You can also use Milkies Freeze, which has a “first in, first out” system for storing the milk.

If you’d like to track the amount of milk that you have in your freezer, check out the Milk Maid app – it will tell you how many days of breast milk you’ve got stored up.

Finally, as you rotate your milk, if you find that you have too big of a freezer stash (i.e., no room for grown-up food), you can consider donating your breast milk to a milk bank or donating it informally.