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Storage and Handling of Breast Milk

There may be times when you need to be away from your baby and unable to nurse. You may need to return to work before your baby has stopped nursing. The baby's father or another person may want to feed the baby. Or, your baby may not be able to breast-feed for a while because of a medical problem. In all these instances when your baby can't be breast-fed, it is best for your baby to be fed milk that has been pumped from your breasts. Thus, you will want to know how to handle and store your breast milk safely for later use.

Preparation and Hygiene

  • Always wash your hands thoroughly before you pump your breasts.
  • A daily shower or bath will keep your breasts clean.
  • After each use of a breast pump, wash all the parts that come into contact with your milk. Use hot soapy water.
  • Tell your doctor and your baby's doctor if you become ill or need to take any medication.

Collection of Milk

  • Pour the milk expressed during one pumping session into a clean hard-sided plastic or glass container. You also may use commercial breast milk storage bags. The thin plastic bottle bags are not recommended as they tear easily. You may use a plastic bottle that has been washed in soapy water and rinsed.
  • Frozen milk is good for 24 hours in the refrigerator after thawing.
  • Premies need smaller serving sizes.
  • Babies who drink pumped milk only occasionally would need single-serving sizes.
  • Tightly cap bottles. Do not store bottles with nipples attached.
  • Label each container with your baby's name and the date and time the milk was expressed.

Storage of Breast Milk

Fresh milk may be kept at room temperature (up to 77F or 25C) for 6 to 8 hours. Cover the container and keep it as cool as possible.

Milk may be stored:

  • In the refrigerator for at least 72 hours after pumping and 24 hours after thawing (assuming the temperature of the refrigerator is 34F to 40F, or 1C to 4 C). Store it in the back of the main body of the refrigerator
  • In a freezer inside a refrigerator for up to 2 weeks after pumping (assuming the temperature of the freezer is 20F to 28F, or -7C to -2C)
  • In an insulated cooler bag with ice packs for 12 to 24 hours.
  • In a separate-door freezer for 3 to 6 months after pumping (assuming the temperature of the freezer is 5F to 15F, or -15C to -9C)
  • In a deep freezer for 6 to 12 months after pumping (assuming the temperature of the freezer is 0 F or below, or -18 C or below).

Thawing of Milk

Milk may be thawed:

  • Slowly in the refrigerator. Volumes of 3 or more ounces (100 or more milliliters) of milk may take several hours to thaw.
  • Relatively quickly under running warm water or by placing it in a bowl of warm water. Be sure the top of the container remains above the water at all times. Do not thaw milk at room temperature.
  • Swirl the container of milk to mix the cream back in.

Warming of Milk

You need only to take the chill off cold milk. You do not need to heat it. You may warm a bottle of chilled milk:

  • under warm running water
  • in a bowl of warm water (be sure the top of the container is above the water at all times)
  • in a purchased bottle warmer (be careful not to overheat).

About Microwave Heating

Authorities recommend AGAINST using a microwave oven or stove top to either thaw or heat expressed milk. Milk can overheat very easily in a microwave. Babies have been accidentally burned by milk that was too hot. Also, many of the immune properties of breast milk can be destroyed by overheating.

Additional Recommendations

  • DO NOT thaw milk by letting it sit out of the refrigerator or freezer at room temperature.
  • DO NOT overheat milk. Overheating will destroy some immune components, and hot milk can burn an infant's mouth.
  • DO NOT leave defrosted milk at room temperature for more than 1 hour.
  • Milk left in the bottle after a feeding should be thrown out and not used again.
  • Milk may be reheated and used for the next feeding if it has not been left at room temperature for more than 1 hour. Throw out any milk left after a second feeding.
  • DO NOT refreeze thawed milk.
  • DO NOT add warm breast milk to frozen milk because it will partially thaw the frozen milk.
  • DO NOT store milk in the door of your freezer, where the temperature may change frequently.
  • Always transport milk on ice in an insulated cooler.
  • For healthy babies who are not in the hospital, it is safe to layer milk collected at different times on the same day in the same bottle. Chill freshly expressed milk in the refrigerator for an hour before adding it to previously frozen milk.
Written by Marianne Neifert, MD, and the clinical staff of The Lactation Program, Rose Medical Center, Denver, CO. 303-377-3016.
Published by RelayHealth.
Last modified: 2009-12-10
Last reviewed: 2009-11-22
This content is reviewed periodically and is subject to change as new health information becomes available. The information is intended to inform and educate and is not a replacement for medical evaluation, advice, diagnosis or treatment by a healthcare professional.
2010 RelayHealth and/or its affiliates. All Rights Reserved.
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