Milk Storage

• From THE WOMANLY ART OF BREASTFEEDING, La Leche League International, Sixth Edition, p. 158-159, 161-162.
  "New research has shown that human milk can safely be kept at room temperature (66-72 degrees F) for up to ten hours because of its remarkable ability to retard the growth of bacteria. Milk can be kept refrigerated for eight days. For longer storage, it can be frozen. Frozen milk can be kept up to two weeks in the freezer compartment of your refrigerator, three to four months in a separate door freezer that is opened frequently. It can be kept six months or longer in a separate freezer that stays at a constant 0 degrees F. Once the milk is thawed, it cannot be refrozen; if the freezer defrosts for any reason, the milk must be discarded.

  After pumping or expressing your milk into a clean container, transfer it into a glass or plastic storage container, baby bottle, or plastic milk storage bag. Use a separate container to refrigerate the milk each time you pump or express. These cooled batches can later be combined for a feeding or for freezing. You can add refrigerated milk to milk that is already frozen, just be sure the amount you are adding is smaller than the amount already frowen so it does not thaw the frowen milk. Allow room for expasion when filling containers for freezing. Do not tighten caps until milk is completely frozen.

  You can freeze your milk in either glass or plastic storage containers. Some mothers store their milk in plastic nurser bags designed for feeding babies. Freezing milk in these less-durable bags can be risky. It is a good idea to use them doubled to aboid tearing. Squeeze out the air at the top, roll down to one inch above the milk, fasten, and place the bag into a container which will hold it upright until it is frozen solid. These bottle liners are not recommended for long term storage." An unopened container of human milk that has been frozen and thawed can safely be kept refrigerated for up to twenty-four hours. It is not known whether or not leftover milk should be discarded after baby has taken some of it from the bottle. Recent studies have shown that human milk actually retards the frowth of bacteria so it may be safe to refrigerate unused milk for later use. Thawed milk should not be refrozen."

• From THE BREASTFEEDING ANSWERBOOK:
  • At room temperature - Term colostrum
  • at 80.6 to 89.6 dgrees F (27 to 32 degrees C) - 12 hours (Nwankwo1988) Mature Milk
  • at 60 degrees F (15 degrees C) - 24 hours (Hamosh 1996)
  • at 66 to 72 degrees F (19-22 degrees C) - 10 hours (Barger and Bull1987)
  • at 79 degrees F (25 degrees C) - 4 to 6 hours (Hamosh 1996, Pittard1985) "In a refrigerator- Mature milk
  • at 32 to 39 degrees F (0 to 4 degrees C) - 8 days (Pardou 1994) "In a freezer-
  • in a freezer compartment located inside a refrigerator - 2 weeks " in a self-contained freezer unit of a refriegerator - 3 or 4 months (temperature varies because the door opens and closes frequently)
  • in a separate deep freeze at a constant 0 degrees F (-19 degrees C)

• From "What to Expect the First Year":
  "Plastic containers are better than glass for collecting and storing breastmilk, not only because glass is breakable, but also because disease-fighting white blood cells in mother's milk have been shown to cling more to glass than to plastic, making them less available to baby.

  Refrigerate expressed milk as soon as you can; if that's not possible, use a sterile cotnainer, in which it will stay fresh at room temperature (but away from radiators, sun, or other sources of heat) for as long as six hours. You can store breast milk for up to 48 hours in the refrigerator, or chill for 30 minutes, then freeze. Fill containers for the freezer only 3/4 full to allow for expansion, and label with the date (always use the oldest milk first). Breast milk will stay fresh in the freezer for anywhere from a week or two in a single-door refrigerator, to about three months in a two-door frost-free model that keeps foods frozen solid, to six months in a freezer that maintains a zero temperature.

  To thaw breast milk, shake the bottle under lukewarm tap water; then use within 30 minutes. Or thaw in the refrigerator and use within three hours. Do not thaw in a microwsave oven, on top of the stove, or at room temperature; and do not refreeze. When your baby has finished feeding on a bittle, discard the remaining milk.

• Information is from Human Milk Banking Association of North America. Executive Director: Lois Arnold, MPH, IBCLC. 5/93, revised 8/95.)
  • Glass or hard plastic are preferred-- baby bottles, Tupperware containers, glass jars, baby food jars.
  • Plastic nurser bags tend to leak and can destroy nutrients found in breastmilk. Fat also adheres to the sides of bags, decreasing available calories and fat soluble nutrients. Use of plastic bags is STRONGLY DISCOURAGED. If thin plastic bags must be used, double bag and store bags in a hard sided container to help prevent tears and punctures.
  • NEVER use a microwave to thaw or heat milk. Microwaves can cause damage to milk components, and milk heated this way has the potential to burn your baby.
  • Never refreeze thawed milk.
  • Use thawed milk within 24 hours.
  • A few smaller portions (1 or 2 ounces) may also be packaged for when a feeding is not enough or when a breastfeeding will take place within 30 minutes.

• I used to freeze milk in Playtex bags (inside Ziploc bags), but I quit and just pumped each day for the next day. Works well for us.
• I always freeze in bottles, usually 3-4 oz per bottle. I throw out anything older than 3 months. Zachary doesn't seem to like milk that's been stored in the refrigerator for more than 1 day, so I freeze everything.
• I don't mix warm with cold milk.
• I'm one of those who pumps right on top of a previous pumping (warm milk over cooled milk), and I've never had a problem doing that with either of the babies I've pumped for. Don't know if you want to add that to the "save time" section, tho, in case it causes thrush for some.