This article is from the Breast Pumps FAQ, by firstname.lastname@example.org (Beth Weiss) with numerous contributions by others.
I requested information about the logistics of pumping milk,
especially for a daycare situation. Here's a summary of responses.
There are at least four methods that people mentioned: disposable
bottles, ziploc-type bags, actual bottles, ice cube trays.
These can be purchased in most grocery, drug, kid stores. Playtex
has 4 ounce sizes. Playtex, evenflo and store brand have 8 oz sizes.
Don't put too much milk in a bag (2-3 oz in a 4 oz bag), since it will
expand when freezing. Most people close the bags with twistie ties;
some use tape. Label the bags with the amount in them and the date.
Misc. points people made:
Evenflo bags have the amounts on the bags--easier to mark. The
newer Playtex bags also do.
Store milk in small amounts to eliminate/limit wasted milk
Store bags hanging until they're frozen (clip to the side of a
tupperware container). This works especially well with
bags that are taped closed.
If you're pumping every day for the next day, there's no need
to freeze the milk. Just store it in bottles for the next
Some people double bag, others say it isn't necessary, because
they've had very little breakage/leakage
Store different amounts (1 oz, 2 oz, 2.5 oz, etc.) so that
bottles of the appropriate size can be made by combining
There are also bags that can be purchased especially for storing
breastmilk. Both Medela and Emeda Egnell sell them.
Note: Nursing Mother's Counsel does not recommend using Evenflo or
Plaxtex bags for either the storage or storing of breastmilk. The
bags are permeable to bacteria and are not thick enough to prevent
freezer burn. Certain factors in breastmilk adhere to the plastic
bags. Medela makes storage bags that do not have these problems.
Buy lots of cheap plastic bottles, and store directly in the
bottles. To use, just defrost in warm water, and add nipple.
Bags vs. Bottles
Bags take less freezer space than bottles
Bags defrost quicker than bottles
Don't need to transfer as many times with bottles
Ice cube trays
Apparently, each cube holds about an ounce, and the daycare
provider just defrosts as many as are needed. There may be concerns
with milk contamination or freezer burn with this method.
Just about everyone recommended silicon orthopedic type nipples.
Several people suggested that a trial-and-error period might be
necessary to find which kind of nipple the baby would take.
Transporting the Milk
Some people bough special "milk transport bags". Some used
insulated bags. For short distances, it probably doesn't matter.
Using the Milk
Bags can easily be defrosted by running them under hot water. They
thaw quickly. Some people then transfer the milk to a plastic bottle.
Others use the Playtex nurser system, and just insert the bag into the
nurser. (Try this with a bag full of water before risking milk).
Some people have heard that breast milk should be defrosted by running
under cold water.
Warning: don't microwave breastmilk.
Some people prepared the bottles at home, others let the daycare
provider make them. Some people take all of the dirty bottles/nipples
home and sterilize them, others have the daycare provider do it.
Nursing Mothers' Counsel recommends defrosting milk by moving it to
the refrigerator 8 - 12 hours before it will be used. Heat and
vigorous shaking can damage milk cells. Milk should be defrosted with
water no warmer than body temperature and gently swirled to mix the
When to Start
Try and build up a backlog of milk in the freezer. Most women don't
pump enough during the workday to totally feed the baby, so you will
need the backlog. Give the first bottle at 3-4 weeks, if you're going
back to work at 6 weeks, so you have time to discover what kind of
nipples the baby likes. (See the Nipple Confusion Survey later in