How to Store, Freeze, and Thaw Breast Milk

Safely storing your hard-earned breast milk shouldn’t require remembering the life cycles of bacteria from your ninth-grade science class. Here’s the info you need to store, freeze, thaw, and use your pumped liquid gold with confidence. (No textbooks required!)

How to store breast milk

• Use storage bags specifically designed for breast milk (they’re thicker than food-storage bags and have a stand-up bottom) or glass/plastic food-grade storage containers with well-fitting lids.

• Date and label every container of breast milk. 

How to freeze breast milk

• If you don’t plan to use your breast milk within four days of expressing it, freeze it. 

• Freeze breast milk in small amounts—2 to 4 ounces—to avoid wasting any that your babe might not finish in a feeding.

• Leave an inch of space at the top of the container to accommodate expansion as the milk freezes. (Cough. Trust us on this one.)

• Don’t store breast milk in the door of either the fridge or the freezer as the temperature fluctuates every time the door is opened. 

• Space-saving tip: If you’re using bags, place them flat in the freezer until they freeze, and then stand them up.

How to thaw breast milk

• Thaw your oldest breast milk first. The first containers you freeze should be the first ones you use, as the quality of breast milk can decline over time.

• Thaw your breast milk in the fridge overnight, put it in a bowl of warm water, or under lukewarm running water. 

• Don’t use the microwave to thaw or heat breast milk because it can destroy nutrients in breast milk and create hot spots, which can burn a baby’s mouth.

Using frozen breast milk

• It’s normal for stored breast milk to separate—just gently swirl bottles to reintegrate the layers.

• Use breast milk within 24 hours of being completely thawed.

• Use breast milk within two hours once it’s been brought to room temperature or warmed.

• You can add freshly expressed breast milk to refrigerated or frozen milk, but cool it down in the fridge before you do.

• Never refreeze breast milk once it's been thawed.

Source: CDC’s Proper Storage and Preparation of Breast Milk

Mamava designs solutions to empower breastfeeding and pumping parents on the go, like our freestanding lactation pods, Mamava’s lactation space locator app, and other helpful resources.

More breastfeeding resources