I was incredibly lucky as a new mom when my daughter took to breastfeeding like a champ. I was home with her, so I never had to worry about pumping or storing breast milk. But the few times I did, in an effort to build up a frozen stash, I always panicked. Had I pumped too much in one bottle? What if she didn't want all of it and that liquid gold was just wasted? And how long does breast milk last, anyway?

The latter question is huge for any pumping moms, but especially those who are trying to build up a stash or need to store milk for a few days, like working moms that may pump on Friday so a caregiver can feed the baby on Monday. Like cow's milk, Baby Center notes that breast milk can spoil if it's not stored correctly, causing it to smell bad and taste sour.

How long the breast milk you've pumped lasts all depends on how you're storing it. The time varies depending on how cold the milk gets, which can mean different things for everyone. Like, a refrigerator can hold pumped milk longer than a cooler full of ice, which is good to know for moms who pump on the go.

Luckily, the Centers for Disease Control and Prevention have some pretty easy to follow guidelines on how long breast milk lasts.


For milk you've just pumped and are planning to give your baby soon, the breast milk can sit out at room temperature (up to 77 degrees Fahrenheit) for six to eight hours. The CDC notes that the milk should be covered and try to keep it as cool as possible.

For moms that pump on the go, an insulated cooler bag with ice packs can keep your breast milk safe for 24 hours. Again, the CDC recommends keeping the milk as cold as possible, so make sure it's always in contact with the ice pack and try not to open the cooler bag too much.

Covered beast milk stored in the back of the refrigerator (not in the door or near the front where cold air can escape when the fridge is open) is good for up to five days. If your fridge has a freezer compartment inside (as in the kind in a mini-fridge and it doesn't have its own separate freezer door), that breast milk can be stored for two weeks.

Trying to build up a stash? You're in luck. A traditional freezer, like the one attached to your refrigerator with its own separate door, can keep your breast milk safe and fresh for three to six months. Storing in a chest or deep freezer? That milk is good for six to 12 months.

Don't forget to use labels on bottles and breast milk storage bags so that you're never confused about how old the milk is. And remember, when breast milk has gone bad, you'll know. It smells and tastes sour, like any other kind of spoiled milk. If you notice that the breast milk has separated during storage, don't worry. KellyMom notes that the cream in the breast milk often rises to the top and simply needs swirling before feeding to your baby to reincorporate the milk.