Pumping & Pooling Breast Milk

Is every bottle of pumped breast milk exactly the same?

The composition and quality of your breast milk, as well as the volume produced, changes over the course of the day. It is dependent on your nutrition and fluid intake among other things. For example, whether or not you take herbal supplements to enhance your milk supply, the amount of time you spend breastfeeding (or pumping) and your overall health can affect your breast milk.

Because of these differences in composition and quality, we advise you to take the cooled breast milk you’ve pumped all day and mix the contents of the various bottles together. This ensures that when you are ready to use this stored milk at a future date, it will all contain similar quality milk. Some moms notice the morning milk has more volume and lower fat content, while the evening milk may have more fat but be lower in volume. By pooling your breast milk, you ensure baby receives nourishment that is more uniform and consistent.

Some important details to bear in mind:

  • You may have to gently warm the milk before pooling it together, so the fat gets mixed back in .
    • Place the bottles on the counter, or in a warm dish of water, for 5 minutes to take the chill off. Then gently swish the contents of each bottle around and combine them all together
  • Use all the milk you pumped in 24 hour period when you pool your breast milk.
  • Once you mix a days worth of milk together, divide up the milk into baggies or bottles in the amounts your baby needs per feeding, like 3 oz. or 4 oz. portions.
    • You may want to have a few smaller volume bottles or baggies of milk saved in case the baby needs a top off after the regular feeding. You will not have to defrost large amounts in these situations; simply use the smaller sizes of frozen milk.
  • Consider removing and defrosting a bottle or baggie every month to ensure the pumped milk has retained its integrity and has not developed any odors or bitter tastes. Some moms experience a problem from the breakdown of the fat cells during the freezing process. This can cause a release of the enzyme lipase that often sours and spoils the frozen milk. This milk will have to be tossed out.
    • Lipase in breast milk can be reduced by a heat process called scalding. Prior to reaching a full boil, scalding will reduce the breakdown of fat cells and prevent the release of lipase. After scalding, the milk can be cooled and then frozen for long-term storage.
    • To scald your breast milk, pour it into a medium-sized pan. Heat until you see a slight bubble at the rim of the pan (pre-boiling state). Turn off the heat when you see these bubbles form. Pour into bottles and let the milk cool down before you freeze it.


Looking for more information about pumping and pooling your breast milk? Share your concerns with a lactation consultant on our team for more personalized guidance.


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