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Each breastfeeding experience is unique. Whether your journey involves occasional pumping, pumping only during work hours, or exclusively expressing breast milk around the clock, it is all a part of breastfeeding. Regardless of how frequently you express your milk, it is essential to handle and store milk with care. Adhering to proper milk storage guidelines ensures that your breast milk continues to contribute to your baby’s health, growth, and development. 

Read below frequently asked questions, tips, and guidelines on breast milk storage.  

Breast Milk Storage Guidelines 
According to the CDC (Centers for Disease Control) guidelines, breast milk is safe for a maximum of 4 hours at room temperature, 4 days in the refrigerator, and up to 6 months in the freezer. For extended storage, breast milk remains acceptable for up to 12 months when frozen. If freezing breast milk, it is best to freeze right away. Refrigerated breast milk can be frozen within 4 days of expression. Ensure your breast milk stays fresh when refrigeration is not possible. When transporting refrigerated or frozen milk, use an insulated bag or cooler along with a frozen cold pack. To preserve its quality, refrigerate or freeze the milk within 24 hours. 

Proper Storage Containers  
Breast milk should be stored in clean food-grade containers such as BPA-free plastic, glass, or silicone. It is also acceptable to store breast milk in disposable storage bags specifically designed for breast milk. Standard disposable plastic bags or inserts intended for bottle feeding should never be used to store breast milk, as freezing may lead to breakage and leaks. Pump accessories, such as breast milk storage bags, may be covered by your insurance. Learn more about breast milk bag coverage by calling the Customer Service line at 844-993-3740.  

Fresh or Frozen? What’s Best? 
All types of breast milk are beneficial. The highest concentration of anti-infective properties is found in fresh breast milk, followed by refrigerated milk and then frozen milk. Offer your baby freshly pumped milk whenever available. Fresh, frozen, and refrigerated milk can be combined. To maintain the integrity of immunological properties, it is advisable to mix breast milk at the same temperature.  

Avoid microwaving breast milk as it may heat unevenly and pose a risk to your baby. Furthermore, microwaving can destroy valuable bioactive components unique to human milk. Choose a gentle thawing method to preserve the quality of breast milk. Thawing can be done in the refrigerator overnight or placed in a bowl of warm water.

Cleaning Pump Parts 
It is advised to clean all your pumping components (excluding tubing) after each use using warm soapy water in a dedicated basin. For additional germ removal, the CDC suggests sanitizing the parts once daily. If you anticipate being without access to a sink, ensure you have an adequate number of pump part sets to last the day. Refrigerating pumping parts between uses is not recommended. 

Important Tips & Reminders 

✔ Remember to start every pumping session by washing your hands for 20 seconds.  

✔ Keep breast milk in smaller portions, typically 2- 4 ounces, to minimize waste.  

Squeeze excess air from the top of the milk storage bag before sealing tightly 

✔ Save space by freezing breast milk bags flat. 

✔ Once frozen breast milk is defrosted; it is good to use within 24 hours. Breast milk should never be refrozen.  

✔ Use leftover breast milk from a feeding within 2 hours of finishing.  

✔ Warm breast milk first, then shake. This technique will mix the fat that may have separated.  

✔ Breast milk can be given cool, warm or room temp to healthy full-term babies.

For additional resources on breast milk storage and preparation, download a printable sheet provided by the CDC here to share with your family and caregivers. 

Do you have a question about breast milk storage? Connect with an International Board-Certified Lactation Consultant at 


Proper Storage and Preparation of Breast Milk. (2020, January 22). Center For Disease Control. 

Heating Human Milk. La Leche League International. (2020, August 6).