What you Need to Know About Storing Breastmilk and Formula
For working moms and moms having trouble with breastfeeding, pumping breastmilk can be a lifesaver. Still, there are some things to keep in mind to be sure your breastmilk stays safe for your baby.
Start with safe breastmilk
Make sure to wash your hands and use clean pump parts before pumping your milk. If you are pumping multiple times during the day, it is ok to store washed pump parts in a plastic bag in the refrigerator between pumping sessions and then sterilize the parts at the end of the day. Follow the directions on your pump to properly sterilize your pump parts at least once per day.
How to store your milk
After you have pumped your milk, you can either store it in bottles or plastic bags specific for storing breastmilk.
- If you plan to give the milk to your baby within 4 hours: you can leave it at room temperature (<75⁰F).
- If you plan to give the milk to your baby within 72 hours: you can store it in liquid form in the refrigerator.
- If you would like to store your milk for longer than 72 hours: transfer it to a plastic breastmilk storage bag and label the bag. You will want to label the bag with the number of ounces as well as the date. To determine the ounces, use the number of ounces on the bottle, not the bag, as it is difficult to measure the ounces once the milk is poured into the bag. Some bags also have a place to write the time the milk was expressed. That is useful information because your milk at the beginning of the day will be different than milk at the end of the day.
Tip: Keep it flat and organized
When you are freezing your milk, lay the bag flat until the milk is frozen. This will make it easier to store the bags if they are all laying flat. Once frozen, organize your milk from oldest to newest.
Tip: Combining milk is cool, just do it at the same temperature
If you want to combine milk pumped from two different sessions, make sure to cool both samples to the same temperature before combining them as the newly pumped milk will be warm and will increase the temperature of the older milk, allowing bacteria to grow.
Tip: Store it in a serving size
It is a good idea to store the milk in typical serving sizes for your baby (ex: 3-4 ounces or less) so that you do not waste your milk. You can also store a few 1 or 2 ounce portions which can be used if the original milk serving was not enough and your baby could use a little more.
How long is frozen breastmilk good for?
It is usually safe to freeze breastmilk for up to 3 months in the freezer section of a refrigerator if the freezer section is separate from the refrigerator section and each has separate doors. The freezer compartment must not be located within the refrigerator (like in small mini-fridges). Place milk away from the door of the freezer and away from the freezer fan. Milk may be frozen for up to 6 months in a deep freezer that is kept at -20⁰F or less. Use the oldest milk first to avoid waste.
Great, now let’s use it.
You have 2 options: Refrigerator or Under Lukewarm Water
Thaw breastmilk in its container overnight in the refrigerator of under lukewarm running tap water or in a bowl of lukewarm water. Do not use hot water as the excessive heat may destroy some of the protective properties of the milk.
Never use a microwave to thaw or warm breastmilk. Microwaves can cause damage to milk components and milk heated this way has the potential to burn the baby’s mouth because of uneven hotspots.
If you defrost your milk in the refrigerator, it must be used within 24 hours. If you defrost it using warm water, you must use it within 2 hours. Because it must be used quickly, only defrost what you think your baby will be eating in the next feeding. It is easier to defrost more milk for your baby rather than throw away the extra milk after every feeding.
How do I store formula?
If you are using powdered formula, store the container in a cool, dry, indoor place. If you are using concentrated-liquid or ready-to-use formula, follow the directions on the container for storage.
Prepared formula should be used within 2 hours after being mixed and within 1 hour of the beginning of the feeding. If you are making a bottle ahead of time to take on the go, keep it in a cool place and use it within 2 hours. Prepared formula can be safely stored in the refrigerator for 24 hours. Be sure to label the prepared bottle with the time and date to ensure its quality. It should not be frozen and thawed.
If your baby does not finish a bottle, you can offer the same bottle within a 1 hour period but after that time it should be thrown away. You can minimize waste by mixing an appropriate serving size for your baby.
Up Next: Baby’s first poo primer
ABM Protocol Committee. (2010d). ABM Clinical Protocol #8. Human milk storage information for home use for full term infants (original protocol March 2004; revision #1 March 2010).
Breastfeeding Medicine: The Official Journal of the Academy of Breastfeeding Medicine, 5(3), 127-130. https://abm.memberclicks.net/assets/DOCUMENTS/PROTOCOLS/8-human-milk-storage-protocol-english.pdf
“Safe Storage of Expressed Breastmilk for the Healthy Infant and Child.” Health Education and Associates, Inc. The Professional Choice for Patient Education Materials and Lois D.W. Arnard MPH, IBCLC.
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