By: Dina DiMaggio, MD, FAAP
When it comes to breast milk, how you store it depends on how soon you want to use it.
Here are some helpful guidelines for storing your breast milk safely.
Before expressing or pumping: Wash your hands and all storage containers thoroughly. Label the date the breast milk was expressed on each container and include your child's name if you are giving the milk to a child care provider. Talk with your child care provider about how they require breast milk be stored and labeled.
Store breast milk in small batches. 2 to 4 ounces is recommended to prevent waste. Any remaining breast milk left in a bottle after your baby is finished with a feeding should be used within 2 hours, or, if quickly refrigerated, used for the next feeding. You can always thaw an extra container if needed.
Refrigerate or chill milk right after it is expressed. Freshly expressed milk can remain at room temperature (up to 77°F or 25°C) for 4 hours (or up to 6 to 8 hours if very cleanly expressed), but it is best to chill as soon as possible.
Breast milk can be placed in the back of the refrigerator (39°F or 4°C). It is best to use refrigerated breast milk within 4 days, but it can be refrigerated for up to 8 days.
To warm breast milk from the refrigerator: Place the bottle in a bowl of warm water or run it under warm water. Microwaving breast milk is not safe due to the risk of scalding your baby with hot milk.
Freeze breast milk if you will not be using it within 24 hours. Breast milk expands as it freezes, so do not fill the milk all the way to the top of the storage container. Again store the milk in the back of the freezer, not the door.
If freezing the milk inside a refrigerator with a freezer that has a separate door (0°F or −18°C), milk may be frozen for up to 9 months.
If the freezer is a chest or a deep freezer (−4°F or −20°C), milk may be frozen for up to 12 months.
To thaw breast milk from the freezer: Put the bottle or bag in the refrigerator overnight, hold it under warm running water, or set it in a container of warm water. Remember that heating breast milk in microwaves is not safe.
Once breast milk is thawed: It can be stored in a refrigerator and must be used within 24 hours.
The Rule of 4's
We know breast milk storage can be confusing, so here is a more conservative approach that you can also go by (and easily remember): 4 hours at room temperature and 4 days in the refrigerator!
Editor's Note: Although these breast milk storage guidelines are appropriate for babies born premature and those who are hospitalized, hospitals may have their own rules. If you have specific questions, discuss these guidelines with your baby's pediatrician and/or hospital.
Where We Stand:
The American Academy of Pediatrics recommends breastfeeding as the sole source of nutrition for your baby for about 6 months. When you add solid foods to your baby's diet, continue breastfeeding until at least 12 months. You can continue to breastfeed after 12 months if you and your baby desire.
Additional Information & Resources:
About Dr. DiMaggio:
Dina DiMaggio, MD, FAAP, is a board certified pediatrician at Pediatric Associates of NYC and at NYU Langone Medical Center. She is the co-author of The Pediatrician's Guide to Feeding Babies and Toddlers, a comprehensive manual written by a team of medical, nutrition, and culinary experts. Follow her on Instagram @Pediatriciansguide.