Breast Milk Storage Questions and Answers

Never refreeze breast milk after it has thawed.

Breast Milk Storage and Preparation

Various factors affect how long human milk can be stored safely. The storage and preparation techniques recommended can help maintain the safety and quality of expressed breast milk for the baby’s health. These guidelines provide information for storing human milk at different temperatures and for preparing human milk after storage.

Human milk storage guidelines

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Before expressing or handling breast milk

Wash your hands well before expressing or handling breast milk.

Wash your hands well with soap and water. If soap and water are not available, use an alcohol-based hand sanitizer that contains at least 60% alcohol.

Mothers can express breast milk by hand or with a manual or electric pump.

If using a pump, inspect the pump kit and tubing to make sure it is clean. Discard and replace moldy tubing immediately.

If using a shared pump, clean pump dials, power switch, and countertop with a disinfectant wipe.

Storing breast milk after expressing

Use breast milk storage bags or clean, food-grade containers to store expressed breast milk. Make sure the containers are made of glass or plastic and have tight fitting lids.

Never store breast milk in disposable bottle liners or plastic bags that are not intended for storing breast milk.

Freshly expressed or pumped milk can be stored:

• At room temperature (77°F or colder) for up to 4 hours.
• In the refrigerator for up to 4 days.
• In the freezer for about 6 months is best; up to 12 months is acceptable. Recommended storage times are important to follow for best quality.

Want to learn more?‎

Do you have other questions, such as where to store breast milk at work or what to do when the power goes out? Visit Frequently Asked Questions.

Storage tips

Clearly label breast milk with the date it was expressed.

Clearly label breast milk with the date it was expressed. Do not store breast milk in the door of the refrigerator or freezer. Storing it further inside will help protect the breast milk from temperature changes when the door opens and closes.

If you don’t think you will use freshly expressed breast milk within 4 days, freeze it right away. This will help to protect the quality of the breast milk.

When freezing breast milk:

• Store small amounts to avoid wasting milk. Store in 2 to 4 ounces or the amount offered at one feeding.
• Leave about one inch of space at the top of the container because breast milk expands as it freezes.

If you deliver breast milk to a childcare provider, clearly label the container with the child’s name. Talk to your childcare provider about any other requirements for labeling and storing breast milk.

Breast milk can be stored in an insulated cooler with frozen ice packs for up to 24 hours when traveling. At your destination, use the milk right away, store it in the refrigerator, or freeze it.

Safe thawing of breast milk

Always thaw the oldest breast milk first.

Remember: First in, first out. Always thaw the oldest breast milk first. Over time, the quality of breast milk can decrease.

You can thaw your breast milk by putting the container in the refrigerator overnight, in warm or lukewarm water, or under lukewarm running water.

Never thaw or heat breast milk in a microwave. Microwaving can destroy nutrients in breast milk and create hot spots, which can burn a baby’s mouth.

If you thaw breast milk in the refrigerator, use it within 24 hours. Start counting the 24 hours when the breast milk is completely thawed, not from the time when you took it out of the freezer.

Once breast milk is brought to room temperature or warmed, use it within 2 hours.

Never refreeze breast milk after it has thawed.

Feeding expressed breast milk

Breast milk does not need to be warmed. It can be served room temperature or cold.

If you decide to warm the breast milk, here are some tips:

• Keep the container sealed.
• Place the sealed container into a bowl of warm water or hold it under warm, but not hot, running water for a few minutes.
• Test the milk’s temperature by putting a few drops on your wrist before feeding it to your baby.
• Do not heat breast milk directly on the stove or in the microwave.

Swirl the breast milk to mix the fat, which may have separated.

If your baby did not finish the bottle, use the leftover milk within 2 hours. After 2 hours, leftover breast milk should be discarded.

Safe cleaning of infant feeding items and pumping equipment

Clean, sanitize, and store all feeding and pumping equipment.

Carefully clean, sanitize, and store pump equipment, baby bottles, and other feeding items to protect your breast milk from contamination. See CDC guidance on how to safely clean and store pump equipment and infant feeding items.

• How to Clean, Sanitize, and Store Infant Feeding Items
• How to Keep Your Breast Pump Kit Clean

Learn more

• Freezing and Food Safety
• Clinical Protocol #8: Human Milk Storage Information for Home Use for Full-Term Infants

Resources

• Supporting Breastfeeding Families in Early Care and Education (ECE) Programs

• Storage, Handling, and Preparation of Breast Milk in ECE Programs

Breast Milk Storage Questions and Answers

Following recommended storage and preparation techniques can maintain the safety and quality of expressed breast milk for the health of your baby. Learn answers to frequently asked questions here.

Why do I see different breast milk storage recommendations?

Many factors can affect how long and where breast milk can be stored. These factors include storage temperature, rising and falling of the temperature, and cleanliness while expressing and handling breast milk. Therefore, it is difficult to recommend exact times for storing breast milk in various locations.

Does the temperature of the room matter?

Yes, if you plan to leave your breast milk on the counter until you use it. This is especially important if you live in a warmer climate or keep your home at a warmer temperature. Place breast milk in the refrigerator if it will not be used within a few hours. Breast milk does not spoil as quickly at cooler temperatures.

How do I store and serve leftover breast milk?

Leftover breast milk can still be used within 2 hours after the baby is finished feeding. After 2 hours, leftover breast milk should be thrown away. To avoid wasting unfed milk, consider storing, thawing, and warming it in smaller amounts.

How can I find the refrigerator and freezer temperature?

Your refrigerator should be 40°F or below, and your freezer should be 0°F or below. If your refrigerator/freezer thermostats do not show the temperatures, use inexpensive, freestanding appliance thermometers . Even if your refrigerator/freezer do show the temperatures, appliance thermometers may be important if you lose power or have mechanical problems.

Can I move frozen breast milk to another freezer?

As long as the temperature of the freezer is 0°F or below, the type of freezer does not matter. The temperature of kitchen freezers is typically 0° F. Deep freezers and chest freezers may be colder than 0°F. Breast milk can be stored at 0° F or colder for up to 12 months, although using it within 6 months is best. Count the age of the milk from the first time it was frozen, regardless of when it was moved.

Moving frozen breast milk between freezer locations should be done quickly to ensure that the milk stays frozen. Pack frozen breast milk on ice packs when moving it from one location to another.

Can I refrigerate breast milk and then freeze it later?

After 4 days of refrigeration, your breast milk should be used or thrown away. Breast milk properties slow the growth of bad bacteria. These properties begin to decline after a few days of refrigeration. If you think you won’t use breast milk within a few days, freeze it as quickly as possible.

Can I mix fresh breast milk with older breast milk?

Mixing freshly expressed breast milk with already cooled or frozen milk is not advised because it can rewarm the older stored milk. It is best to cool freshly expressed milk before combining it with older, previously cooled or frozen milk. Also consider storage duration guidelines for breast milk. For example, if combining cooled milk pumped on different days, base the duration of storage on when the older milk was first stored.

The power went out! Do I throw out my frozen breast milk?

It depends on how long the power is out and how defrosted or warm the breast milk becomes. Freezers, if full and left unopened during a power outage, will keep food safe for about 48 hours. If the freezer is half full, they will keep food safe for about 24 hours.

The refrigerator will keep food cold for about 4 hours if it is left 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 in the refrigerator and use it within the next day or throw it away.

Where can I store my breast milk at work?

Expressed breast milk is 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 sanitation or safety health risks. However, it is important that the breast pump equipment be cleaned, dried, and stored in a clean environment to protect the equipment and expressed breast milk from contamination.

How do I store expressed breast milk while traveling?

Expressed breast milk may be stored and transported in an insulated cooler bag with frozen ice packs for up to 24 hours. Or the milk can be frozen in dry ice following these safety precautions.

Once breast milk is cooled, keep it cool until it is used. Breast milk that has been transported in an insulated cooler bag with frozen ice packs can be refrigerated or frozen. Breast milk frozen with dry ice can be transferred to the freezer or to the refrigerator if you plan to use it in the next few days.

Depending on the destination, if no reliable breast milk storage is available, consider using temperature-controlled shipping to transport breast milk. If this is not an option, discard the expressed breast milk. Continuing to express breast milk regularly will help a mother maintain her breast milk supply until she and her nursing infant or child can be reunited. Visit CDC’s Travel Recommendations for the Nursing Families webpage to learn more.

Traveling by air?‎

You can 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.