Your milk is a living thing! It is rich in antibodies that are constantly killing off bacteria. For that reason, it is very stable and remains safe even after it’s been expressed. Guidelines for human milk storage are different than formula, or even than pasteurized cow’s milk that you commonly buy at the grocery store.

You may find a wide spectrum of “rules” written about the safety of pumped breast milk at various temperatures. Why is there so much variability? The simple answer is that research is conducted in controlled situations for different purposes. Conditions for milk storage in your home are very different than in a lab. For example, pumped milk will last longer in a refrigerator that is never opened. A hospital environment with fragile, premature babies requires that milk be handled much more carefully than a home environment with a term baby.

What follows is a middle-of-the-road approach that considers the research as well as the less than perfect conditions of a home environment. The guidelines below assume that your baby is full term and healthy.

Fresh (not frozen) pumped breast milk at room temperature: 4 hours or until the next feeding. (No need to warm it up!)

Pumped breast milk in the refrigerator (not previously frozen) : 5 days

Pumped breast milk in freezer: 3 months

Pumped breast milk in deep freeze: 6 months (possibly longer if freezer rarely opened)

Whenever possible use fresh, room temperature or refrigerated pumped breast milk. Just as a freshly picked apple is more nutritious than an apple that’s been in cold storage for 3 months; your milk is most nutritious immediately after it’s been expressed. In addition, freezing destroys some of the live cells in your milk. So, if possible, store your precious milk in the fridge, leaving the frozen stash for emergencies.

If you plan to freeze your milk, make sure you use storage containers that are appropriate for a freezer. Fill the containers leaving at least ½ inch of head space. Glass containers, BPA -free plastic rigid containers and plastic storage bags are all acceptable. Be sure the bags are freezer safe, however. No one wants to find a burst bag of your precious milk in the freezer!<

If you are having a hard time figuring out a system for storing your milk for your return to work, be sure to ask for help. Renee Beebe is available for return -to -work phone consultations—perfect for helping you figure out the details of breast milk storage and establishing a routine that works for you and your baby.