Breastfeeding: Storing Your Breast Milk

Mothers can pump their breasts for milk and then store it for supplemental feedings or when they are away from their baby. Glass or hard plastic containers are the best storage containers for human milk, especially if it is to be frozen and stored for weeks. Special storage bags designed for storage of human milk are available from some breast pump manufacturers. Freezing may cause the seams of disposable bags created for bottle feeding to split, but double-bagging may prevent this problem.

If using bags, squeeze the air from the top before sealing tightly with a twist-tie or other clamp. Fasten the clamp at least 1 inch beyond milk level to allow for expansion with freezing. Place storage bags upright in another container or the milk will leak.

If you pump both breasts at once, and the amount of milk obtained will fill one bottle or bag no more than two-thirds full, you may combine the contents in a single container by carefully pouring the milk from one container into the other. If combining milk from different pumping sessions, chill the recently pumped milk in the refrigerator before adding it to milk already cooled or frozen. Store only 2 to 4 ounces per container. It is easier to thaw a second container of milk than to watch your valuable milk be poured down the drain. Label each collection container with the date and any medications you have taken.

Health considerations when storing your breast milk:

  • "Fresh" breast milk contains the most active infection-fighting properties, followed by refrigerated milk, and then frozen breast milk.

  • Fresh milk may be left at room temperature of 66°F to 72°F (19°C to 22°C), but it must be used within 10 hours.

  • It probably is better to refrigerate fresh milk when it is not going to be used within 60 minutes. The refrigerator should be at a temperature of 32°F to 39°F (0°C to 4°C). Do not freeze milk for a high-risk baby when that milk has been refrigerated for more than 24 to 48 hours.

If refrigerated milk will not be given to your baby within one week, freeze it for later use. Milk can be frozen for the following lengths of time:

  • up to two weeks if the freezer compartment is within the refrigerator. (You must open the refrigerator door to reach the freezer with this model.)

  • three to six months in a freezer that is part of a refrigerator unit but has a separate door.

  • six to 12 months in a separate, 0°F (-19°C) "deep" freezer.
    To keep milk cool when a refrigerator is not immediately available, or to transport refrigerated or frozen milk, place it in an insulated bag or cooler with a frozen cold pack.

Pumping Your Breast Milk

Some mothers want to pump their milk so that a bottle can be given to their baby. There are several milk expression (pumping) techniques. With hand expression, a mother compresses the milk sinuses by hand to remove milk. Mechanical breast pumps remove milk by creating suction, and a few also have features that compress milk sinuses to some degree. Generally, the milk-ejection reflex is triggered during milk expression sessions, especially with frequent and regular pumping.

There are several kinds of mechanical pumps available including mini-electric, battery-operated, and hand (manual) breast pumps. These pumps were designed to obtain milk for an occasional "relief" feeding, not for frequent or long-term milk expression. If you need to pump on a long-term basis, such as returning to work or if your baby is unable to breastfeed directly, you will want to choose a hospital-grade, electric breast pump. This type of pump is built for frequent and prolonged milk expression, or to both establish and then maintain full-milk production. These pumps automatically cycle using suction with release of suction - similar to a baby's sucking action. A double collection kit, which allows you to pump both breasts at once, is recommended for these breast pumps.

The hospital nurses, an international board-certified lactation consultant (IBCLC), or a breastfeeding support leader will know of breast pump rental stations in your area, or where you can purchase one.

Online Medical Reviewer: Akin, Louise RN BSNBowers, Nancy A. RN, BSN, MPHMarealita M. Pierce, MD

Date Last Reviewed: 4/2/2010

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