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Before each expression

  • Wash your hands with warm water and soap and dry using a clean towel

  • Assemble your clean pump kit after washing your hands

  • Clean your breasts using a clean damp cloth, wiping your nipple first and then breast

  • If a pump is being used, the pump parts that touch your breast or milk must be washed, rinsed and sterilized once a day. If you pump two or more times a day, rinsing between sessions is sufficient.

  • After pump parts have been sterilized, place in an OPEN plastic Ziploc bag until next use. (Bacteria grows on kitchen counters and placing the sterilized parts on the counter will contaminate them.)

  • If you are not using a pre-sterilized container, sterilize milk container by boiling for 5 minutes

During expression

  • Massage the breast gently before and during pumping, being careful not to touch the nipple

  • Handle the container lid with caution. If you are collecting directly into the container that you will deliver to the Milk Bank, open it and place the cap face up on the table or counter surface. If you are pumping into another container, leave the storage container closed until you are finished pumping. Do not touch the lid of the container or the inside of the cap or the container.

After expression

Refrigerate or freeze the milk within 30 minutes of pumping. You may refrigerate the milk for up to 24 hours before freezing. If there is room for more milk in the container after one session, you may add to it before freezing. Milk needs to be stored in the coldest part of the freezer – usually at the back, or ideally, in a deep freezer.

Do not fill the container to capacity. Leave  a 0.5-inch (13 mm) gap at the top to allow for expansion of the milk as it freezes.

Label the container with the date of expression and your donor ID number using a permanent marker. If combining 2 days of milk, please label milk with the first date of expression. Milk may be stored in the fridge up to 24 hours or fresh milk can also be poured over frozen milk after being chilled in the fridge for 30 minutes.


Clean, food safe (BPA free), milk storage bags are best for milk storage. Clean, rigid plastic containers may be used but Ziploc baggies should not be used for milk storage.

NorthernStar is happy to provide milk donors with milk storage bags free of charge. They can be picked up at the milk bank, at any milk drop location or milk storage bags may be sent to donors directly.

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