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Frequently Asked Questions

Why have I seen different recommendations for storing breast milk?

There are many different factors that can affect how long breast milk can be stored in various locations, such as storage temperature, temperature fluctuations, and cleanliness while expressing and handling breast milk. These factors make it difficult to recommend exact times for storing breast milk in various locations.

Does the temperature of the room matter if I plan to leave breast milk on the counter until I use it?

Yes. If you live in a warmer climate or keep your home at a warmer temperature, you should use breast milk sooner or place it in the refrigerator if it will not be used within a few hours. Breast milk does not spoil as quickly at cooler temperatures.

How can I determine the temperature of my refrigerator and freezer?

Chilling and freezing breast milk to proper temperatures is one of the best ways to slow the growth of bacteria. To be sure that your refrigerator is doing its job, keep its temperature at 40°F or below. The freezer should be at 0°F. Because few refrigerator controls show actual temperatures, using an inexpensive freestanding appliance thermometer will allow you to monitor the temperature and adjust the setting of the refrigerator and freezer if necessary. This may be important if you lose power or have mechanical problems.

If I don’t use breast milk stored in the refrigerator within a few days, can I still freeze it to use later?
After 4 days of refrigeration, your breast milk should be used or discarded. Breast milk has properties that slow the growth of bad bacteria. These properties begin to decline after a few days of refrigeration. To help retain the protective actions of breast milk against bacterial growth, freeze breast milk sooner rather than later if you won’t use it within a few days.

The power went out! Do I have to throw out all of my stored frozen breast milk?

Your breast milk might still be safe, but it depends on how long the power is out and how defrosted or warm the breast milk becomes. Freezers, if left unopened and full during a power outage, will keep food safe for about 48 hours (about 24 hours if half full). When freezers are full, the other frozen items help keep the freezer colder longer. The refrigerator will keep food cold for about 4 hours if it is unopened. While the power is out, keep the freezer and refrigerator doors closed as much as possible.

Once the power is back on, check the condition of your stored breast milk. Frozen breast milk that has started to thaw, but still contains ice crystals can be refrozen. If your breast milk has completely thawed, but still feels cold, put it into the refrigerator and use it within the next day or discard it.

Where can I store my breast milk at work?

Expressed breast milk is a food and may be stored alongside other foods in any refrigerator that is appropriate for food storage. Employers, coworkers, cleaning staff, other family members, and childcare providers should not consider or treat breast milk as a biohazard. Storing breast milk in a shared refrigerator and washing pump parts in community break rooms are unlikely to pose health risks (sanitary or safety issues); however, it is important that the breast pump equipment be cleaned, dried, and stored in a sanitary (clean) environment to protect the equipment (and expressed breast milk) from contamination.

What are the recommendations for properly storing expressed breast milk while traveling?

Traveling by air?

  • You are allowed to carry more than 3.4 ounces of breast milk in your carry-on bag, as well as ice and gel packs.
  • The Transportation Security Administration (TSA) has specific screening procedures for anyone traveling with breast milk.
  • Consider keeping a copy of the TSA regulations in your carry-on bag.

Expressed breast milk may be stored and transported in an insulated cooler bag with frozen ice packs for up to 24 hours, or else frozen in dry ice (follow safety precautions when handling dry ice). Once breast milk is cooled, it should remain cool until it is consumed. Breast milk that has been transported in an insulated cooler bag with frozen ice packs can subsequently be refrigerated or frozen.

Depending upon the destination, if no reliable breast milk storage is available, a mother traveling with expressed breast milk could consider temperature-controlled shipping as an option for transporting breast milk, or discarding her expressed breast milk. Continuing to express breast milk regularly will help a mother to maintain her breast milk supply until she and her nursing infant or child can be reunited. Visit CDC’s Travel Recommendations for the Nursing Mother webpage to learn more.

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