Storing Breastmilk & Preparing it for Feedings

Human milk is a fresh living food with many antioxidant, antibacterial, prebiotic, probiotic & immune-boosting properties, in addition to nutrients.

Breastmilk has good bacteria, which establishes normal gut flora, and probiotics, which ward off bad organisms.

Feed your baby the freshest available milk first. 

Milk quality is best when it's fresh, and current antibodies fight infections you and your baby were recently exposed to.

Melatonin levels in your breastmilk are highest at bedtime, to help your baby sleep. If you are pumping, consider trying to feed your baby that milk at bedtime. If it's hard to keep track of, DON'T obsess over this! It probably doesn't make a huge difference!

Storing milk sacrifices a bit of your milk's qualities, which is explained below. 

Storing freshly pumped milk

Keep your breastmilk cool and clean. 

Bacteria grows faster in warm air, so keep the temperature cooler than 80 o F.

Fewer bad bacteria means you can store your milk safely for a longer time.

Keep things clean while pumping to limit the bacteria hanging around.​

  • There’s no need to discard the first drops of milk when you start pumping. 
  • Wash equipment in hot soapy water and rinse, or wash in the dishwasher.
  • Air dry, or dry with paper towels.

Containers: Use glass or food grade plastic that’s BPA free. 

Dry erase markers are handy to use to write the date and time of pumping on the bottles or lids. Just wipe it off!

Preparing stored breastmilk for feedings

Cooler breastmilk is better. It gives your baby more milk fat than warm milk does.

  -Refrigerated milk at 40 o F contains solid fat which floats in the milk.

  -This solid fat melts to oil fat at body temp (98.6 o F).

  -The oil fat in warm milk sticks to the side of the bottle and gets left behind. So, less fat gets to your baby. 

To thaw frozen breastmilk

  - It’s best to set frozen milk in the refrigerator overnight.

  - Or, run it under warm water, set it in a container of warm water, or use a waterless warmer.

  - Don’t refreeze thawed milk. There’s too little research on this.

Warming breastmilk, if your baby won’t drink it cold.

  - Warm breastmilk over 20 minutes in lukewarm water (less than 104 o F).

  - The milk is body temp (~98.6 o F) if you can’t feel a drop of it land on your wrist.

  - Don’t microwave or heat the milk in a hot water bath (~175 o F). Overheating inactivates the good stuff. 

Declining quality of stored milk – what is known.

  Frozen breastmilk (-4 o F): 

    0oF keeps foods safe from bacterial contamination, but enzymes may remain active,

    which changes milk quality.

  • Frozen 6 weeks – has the same good bacterial viability as fresh milk.
  • Frozen 3 months – less fat, protein, & calories. Lower lactoferrin levels and activity
  • Frozen 1-5 months – very low vitamin C levels
  • Frozen 6 months – colostrum’s cytokines, IgA, & growth factors remain stable.

  Refrigerated breastmilk (40 o F): 

  • 48 hrs – IgA, cytokines and growth factors are good
  • 4 days – Lipids and lipase are stable
  • 5 days – Lactoferrin is stable   

Kay Anderson MD, IBCLC

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