Health Library
Breast Milk: Collection, Storage and Use

How Do You Collect, Store and Use Expressed Breast Milk for Infants?

  • Wash your hands before pumping.
  • Make sure you use a clean collection kit. Follow the instructions that came with your pump for cleaning pump parts between each use.
  • Sit comfortably. Think about your baby or look at a picture of your baby. Relaxation techniques can help increase the amount of milk removed from the breast.
  • Apply a warm wet cloth for a few minutes before pumping to help with milk release from the breast. A warm wet diaper works well to retain the warmth.
  • Gently massage the breast before and during pumping to increase the amount of milk removed.
  • Check to make sure the flange (the piece that fits over the nipple) is the correct size when pumping milk. Your nipple should not rub the barrel or appear tightly squeezed when the pump is on. The wrong flange size can lead to decreased milk production and pain with continued use.
  • If your pump has a vacuum control, use only as much suction as is needed to keep milk flowing. Adjust to your comfort level.
  • Pumping usually takes 10 to 20 minutes per side for a single pump. Double collection kits will decrease the amount of time needed for pumping to approximately 15 minutes total.

Storing Your Breast Milk

  • Pumped milk may be stored in standard baby bottles (glass or plastic). Special bags are also available for human milk storage for home use. Squeeze air from the top of bags before sealing. Seal bags with a twist tie or clamp and place upright to prevent leaking. Label each collection container with the date the milk was pumped.
  • If you collect more than one bottle full of milk, mix the contents of both containers by swirling gently before placing in refrigerator or freezer.
  • Milk will expand during freezing, so fill container ¾ full. You may combine milk from two different pumping times if needed. Store only 2 to 4 ounces per container so you don’t waste milk by having to thaw more than you need!
  • To transport milk, place it in an insulated bag or cooler with a frozen cold pack.
  • Fresh breast milk contains the most active anti-infective properties, followed by refrigerated, and then frozen breast milk.

Human Milk Storage Guidelines for Well Infants

  • Fresh milk at room temperature—No longer than six hours at 25° C / 77° F
  • Fresh milk refrigerated at 4° C / 39° F—No longer than five days
  • Frozen milk in freezer section of refrigerator with separate door—No longer than six months
  • Frozen milk at 0° F / -19° C or lower—No longer than 12 months
  • Frozen milk thawed in refrigerator—No longer than 24 hours
  • Fresh milk in cooler with frozen gel packs—No longer than 24 hours at 15° C
  • Milk left in bottle after infant has begun feeding—Use within one hour and do not store for later use.

Handling and Use of Expressed Breast Milk

  • Wash your hands before handling milk.
  • Thaw breast milk by placing the collection container in the refrigerator for several hours or overnight.
  • Do not refreeze milk once it has been thawed.
  • To warm refrigerated or frozen milk hold the container of milk under warm running water. You may also place it in a container of warm water. The water level should not touch the bottle lid or top of the bag.
  • Milk should never be warmed in the microwave. The microwave can create hot spots in the milk. Microwaving or heating milk in very hot water may also decrease the anti-infective properties of human milk.
  • Your milk separates during storage and the cream (fat) rises to the top. Gently swirl the bottle of milk to mix it. Avoid vigorous shaking.

Contact Us

For additional information on this Health Topic, call the Center for Breastfeeding Medicine at 513-636-2326.

Last Updated 03/2022

Reviewed By Allison Neace