Tips & Resources / Newborn / Milk Storage and Handling

Milk Storage and Handling

Photo by Lucy Wolski on Unsplash

For those who want to have a relief bottle or create a stash for going back to work, here are some guidelines to help make sure your precious commodity is being handled with care:

Always wash your hands prior to expressing milk (manual, hand pump, or electric pump). If you are using a pump, please make sure all of your pump parts and collection bottles are clean prior to pumping. If you’re storing in bags, make sure they’re specific for storing human milk, and please do not reuse.

  • Be sure to use a container with a solid lid to prevent contamination.
  • Breast milk can be stored at room temperature (66-72 degrees F) for 4-6 hours.
  • Freshly expressed in a cooler with frozen gel packs for up to 24 hours.
  • In the core of the refrigerator for 5-7 days (35-40 degrees F) not the door.
  • In the core of the freezer for 3-5 months (-4 +/- degrees F) not the door.
  • Deep freezer 6 months to 1 year (0 degrees F)
  • We suggest plugging your freezer or deep freezer into an emergency power circuit in case of a power failure.
  • Be careful when combining EBM (expressed breast milk) bottles: if you have a bottle in the fridge and you want to add freshly pumped milk, you must refrigerate the fresh milk and bring it to the same temp as the cold milk before mixing bottles. Don’t mix warm with cold:
  • Previously frozen milk that has been thawed in the refrigerator but not warned can stay at room temperature for 4 hours, in the refrigerator for 24 hours, and cannot be re-frozen.
  • Previously frozen and brought to room temperature can be used for the current feeding then stored in the refrigerator for up to 4 hours (next feeding) but then thrown away.
  • If the baby has started their bottle-feeding but didn’t finish the entire bottle, you can leave it at room temp for one more feeding. After that the remaining milk must be thrown away.
  • If it’s frozen, thaw either by a slow defrost in the fridge, or you can put it in warm water. NEVER microwave to defrost or heat it. Once the milk has been warmed, you can’t refreeze or refrigerate – if the baby doesn’t take all of the milk, you can leave it at room temp for one more feeding. After that, it should be thrown away.
  • Bottles vs Bags: it’s imperative to use bags that are designed for human milk storage, please do not use zip top bags! If using bags or freezing, we recommend lying them flat until they freeze, then putting them in date order in a file type system or stored by week in a large zip top bag; it helps to organize the milk. ALWAYS mark the date on the bag! Use the oldest milk first.
  • When freezing, it’s recommended to have smaller ounces available versus having to defrost a larger amount of milk (ie: 2oz vs 5oz) when you’re ready to use it.
  • Milk with a soapy or sour odor/taster: this happens from an enzyme called “lipase” which causes fat to breakdown. The milk is still safe to give to the baby. If you’re concerned about it, you can scald the milk to inactivate the lipase. Scalding is heating the milk to about 180 degrees F, or until small bubbles form around the edge of the pan, then chill quickly and store until use.
  • The fatty cream will separate and rise to the top during storage. Gently swirl, do not shake, to mix and always check the temperature before giving it to the baby.

Adapted from: Best Practice for Expressing, Storing and Handling Human Milk, Frances Jones and Mary Rose Tully, HMBANA, 2ND Edition 2006

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