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How to store breastmilk

07/08/2021 Pediatrics

Breast milk can be handled in different ways to be consumed either immediately or reserved as part of a milk bank. It all depends on the use you want to give it.


Some general rules:

  • Always wash your hands before extracting and handling the milk, and keep the pump and containers clean where you will keep the milk.
  • For the containers where you will store the milk, there are many available in the market, or you can use plastic or glass containers, but make sure they have a plastic lid and not metal because these can contaminate the milk if they rust. We do not recommend using urine collection bottles.
  • Always offer your baby the freshest milk possible, and reserve milk from your bank for emergencies.
  • Label with date/time when you extract.
  • You can warm the milk to body temperature by putting the bottle in a jug of warm water or holding it under running warm water. NEVER use a microwave to defrost breast milk, and be caution for heating it up with*, this can cause hot spots, which can burn your baby's mouth.
  • Milk that comes into contact with your baby's saliva is milk that must be consumed. If there are leftovers, they cannot be reused, refrigerated or re-frozen, due to the risk of bacteria proliferation, it can only be consumed within the following hour.


How to handle extracted milk:

When you first express your milk, you can choose several storage options, considering the estimated time of consumption:

  • Immediate Consumption. At a maximum room temperature of 25 ° C, it lasts a maximum of 6 hrs.
  • Consumption during the day. Refrigerate it, at a temperature of 0 to 4 ° it will last a maximum of 5 days. 
  • Consumption on another day. It depends on when you plan to use it, suppose you plan to use it in the week (considering 5 days max.), You can keep it in the refrigerator, if it is for a more extended amount of time, consider these guidelines:
    • Freezer from the refrigerator. Approximately two weeks. This is due to the constant opening-closing of the refrigerator.
    • Freezer separate from the refrigerator. A maximum of 6 months. It opens less than a built-in freezer.
    • Exclusive Freezer. A maximum of 12 months. We are talking about a separate freezer, without a refrigerator, exclusively for the use of breast milk.

Use these guidelines for your milk bank.


Defrosting breastmilk:

  • If you find yourself in need of using milk from your bank (frozen milk), try to defrost the oldest one, this way your bank will be kept “fresh”.
  • Do not defrost the milk at room temperature, due to the risk of bacteria proliferation, it is advisable to defrost it as described above, if you are not going to defrost it immediately, try to maintain the cold chain, that is, from the freezer to the refrigerator and from the refrigerator it can be transported in a cooler with ice until it can be heated. 
    • milk from the freezer to the refrigerator: 24 hrs.
    • milk from refrigerator to refrigerator with ice: 4 hrs.
    • milk from the freezer to the fridge with ice: 24 hrs.
  • All frozen milk that has been thawed cannot be refrozen under any circumstances.


Consistency and milk flavor:

  • During the milk preservation process, it is normal to see a layer of cream. Just shake the milk a little to integrate it again. It does not mean that it is spoiled.
  • Your thawed milk may smell funny; some women report a sour, stale or soapy smell. This is due to the change in the structure of lipids by the freeze/thaw process. It does not mean that it went bad; if it is handled within the correct time parameters, baby can consume it.
  • Your baby may not accept bottle-fed breast milk at first, and this is normal. Again, if you have followed the recommendations for handling and storing breast milk, it doesn't mean the milk is spoiled but rather refers to the fact that the baby prefers to take "directly from the source" rather than from a bottle.

If this is the case, seek support from a lactation consultant to find the best way for your baby to breastfeed even if you are not around.


Final recommendations:

  • When freezing the milk, try to place it as far back as possible and away from the door as possible.
  • Remember to clean your pump, as well as its accessories constantly, breast milk contains fat that, if not cleaned immediately, sticks to the components and makes subsequent cleaning difficult. In addition to that, a correct cleaning keeps milk free from bacteria.
  • You can join several extractions of the day on the condition that both are at the same temperature; otherwise, there may be an imbalance in the composition. If you have milk in the refrigerator and you have just expressed yourself, first put the freshly expressed milk in the fridge and later mix it with the one you already had previously.
  • There is no bottle or nipple on the market that is "the best" for breastfeeding. Ergonomically, your nipple, when sucked by your baby, sticks to his palate and stretches to reach the deep part of his mouth; no bottle or nipple has replicated this stretchiness. These, being made of a semi-rigid plastic, enter the mouth flat and do not achieve that position.

With that said, you will likely invest a bit until you find the bottle that will fit your baby.


* The use of the microwave is not recommended because it can destroy most of the living cells that breast milk contains, although it does not alter its nutritional value. 

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