Breastmilk storage & freezing basics for pumping moms
After you pump that “liquid gold” — breastmilk — you’ll want to handle and store it carefully to make sure it’s as safe and nutritious going into your baby as it was coming out of you.
Here are some tips and tricks for the best ways to save up your pumped milk until it’s ready to feed to your little one.
Basic breastmilk storage
Store your breastmilk in clean glass baby bottles or hard BPA-free plastic bottles with tight-fitting lids. You can also use milk storage bags, which are made for freezing human milk. Do not, however, use disposable bottle liners or other plastic bags to store breastmilk. (Money-saving tip: Storage bottles or bags to refrigerate or freeze your breastmilk also qualify as tax-deductible breastfeeding gear.)
After each pumping, remember to…
Refrigerate breast milk if it will be used within 24 hours.
Label the date on the storage container before filling it. (Include your child’s name if you are giving the milk to a childcare provider.)
Gently swirl the container to mix the cream part of the breastmilk that may rise to the top back into the rest of the milk. Do not shake the milk, though — this can cause some of the milk’s valuable parts to break down.
Refrigerate or chill milk right after it is expressed. You can put it in the refrigerator, place it in a cooler or insulated cooler pack, or freeze it in small (2 to 4 ounce) batches for later feedings.
If the milk will not be used within 24 hours, it should be frozen — but only for a maximum of 3 to 6 months. Date it when you freeze it.
Try to leave an inch or so from the milk to the top of the container, because it will expand when freezing.
Wait to tighten bottle caps or lids until the milk is completely frozen.
Store breast milk in the back of the freezer, not on the freezer door, since he door is the warmest spot in the freezer. This will help you avoid unintentionally defrosting the milk, which can happen with frequent openings and closings of the door.
Tips for thawing and warming up milk
Clearly label milk containers with the date the milk was pumped/expressed. Use the oldest stored milk first.
Breastmilk does not need to be warmed. Some moms prefer to take the chill off and serve at room temperature, while other babies don’t mind it served cold.
Thaw the bottle or bag of frozen milk (1) by putting it in the refrigerator overnight, (2) by holding it under warm running water, or (3) by setting it in a container of warm water.
When heating baby’s milk, always shake the liquid to even out the temperature and test on top of your hand – not the wrist (this is one of the areas least sensitive to heat) – before feeding. Milk that’s “baby-ready” should feel lukewarm.
Use thawed breastmilk within 24 hours, and don’t re-freeze thawed milk.
Storing fresh breastmilk for use with healthy full-term infants
Things to know
Room temp (up to 77°F)
Up to 3 to 4 hours is best.Up to 6 to 8 hours is okay for very clean expressed milk.
Containers should be covered and kept as cool as possible. Cover the container with a clean cool towel may keep milk cooler. Throw out any leftover milk within 1 to 2 hours after the baby is finished feeding.
39°F or colder
Up to 72 hours is best.
Store milk in the back of the main body of the refrigerator. When at work, you can place your expressed milk in the refrigerator. Use a canvas or insulated bag that blends in with your coworkers’ lunch bags, and place it at the back of the refrigerator.
0°F or colder
Up to 3-6 months is best.
Store milk toward the back of the freezer where the temperature is most constant. Milk stored at zero degrees F or colder is safe for longer durations, but the quality of the milk might not be as high.
Storing thawed breastmilk
Room temperature (60°F to 85°F)
Refrigerator (39°F or colder)
Up to 1 to 2 hours is best. Up to 3 to 4 hours is okay.
Do not refreeze.
Two ways to heat breastmilk or formula
For bottles with disposable inserts, or hard plastic and glass bottles.
In hot tap water: Place bottle under hot, running tap water until the desired temperature is reached. This should take one to two minutes.
On the stove: Heat water in a pan. Remove the pan from the heat and set the bottle in it until it’s warm.
Follow the manufacturer’s recommendations for preparing bottles before filling them with milk.
Transport bottles and food in an insulated cooler when traveling with the baby. Breastmilk that’s left out of the refrigerator or without a cold source for more than two hours should not be used. Cold temperatures keep most harmful bacteria from multiplying.
Don’t put a bottle back in the refrigerator if the baby doesn’t finish it. Harmful bacteria from a baby’s mouth can be introduced into the bottle during feeding; they can grow and multiply even after refrigeration (some bacteria can grow at refrigerator temperatures) and reheating.
Don’t place dirty diapers in the same bag with bottles or food, as bacteria from a dirty diaper can easily spread to baby’s food.