An electric pump is more efficient and faster than a hand pump.

How to Check the Freshness of Breast Milk

by Kathryn Rateliff Barr

Many moms pump breast milk because they work or want to go out without resorting to formula. If you follow appropriate collection and storage guidelines, determining the freshness of your breast milk is easy because La Leche and Texas Health Department published guidelines recommend that you write the pump date on the collection container. Only store breast milk for the time recommended, adjusting for the temperature of your storage method, and toss milk if it does not meet storage guidelines.

Stored at Room Temperature

Pump and store the breast milk in a sterile container. If the breast milk is colostrum, defined as pumped within six days of your baby’s birth, you can store it at 80.6 to 89.6 degrees Fahrenheit for up to 12 hours, according to guidelines published in La Leche League’s “Breastfeeding Answer Book. Mature milk placed in a cooler with a freezer pack is fresh for 24 hours when the temperature is 60 F, 10 hours at temperatures ranging from 66 F to 72 F and four to six hours if the temperature is below 80 F.

Check the time and date on the container and the temperature of the milk to ensure it meets these guidelines. If it doesn’t meet the guidelines listed in Step 1, throw it away.

Set the container in a cup of warm water if you want to warm the breast milk up. Never place it in the microwave for heating. Shake well to remix the milk with the fat content before feeding it to your baby.

Stored in the Refrigerator

Store breast milk in a refrigerator to extend its freshness. Mark the date and time of pumping before you place it in the refrigerator. If you pump it at the office, you might label it as breast milk to ensure that no one assumes that it is cow’s milk or creamer.

Store the milk below 40 F for up to eight days, according to La Leche guidelines or five days, according to the Texas Department of Health. Medela guidelines state five to seven days. If your refrigerator temperatures don’t stay below 40 F, use the guidelines for milk stored at room temperature. For breast milk previously frozen and thawed, feed it to your baby within 24 hours of thawing.

Smell the breast milk if you have any doubts about its freshness, advises the Texas Department of Health, and throw it out if it smells sour.

Stored in a Freezer

Freeze breast milk you don’t plan to use within a few days. Label it appropriately and use the oldest milk first. Milk stored in the freezer section inside your refrigerator is fresh for approximately two weeks. Milk stored in a separate refrigerator freezer compartment remains fresh for about three to four months and six months or longer in a deep freeze where the constant temperature is below 0 F.

Thaw the breast milk by holding it under running warm water or sitting in a container of warm water on the counter for less than 30 minutes. Feed it to your baby immediately. Thawing the milk in the refrigerator allows it to remain fresh for 24 hours.

Never refreeze breast milk once it has been thawed -- it’s safer to throw it out once it’s older than 24 hours in the refrigerator. Separation of milk and milk fat is natural, but a sour odor is not. If the milk smells bad, toss it.

Items you will need

  • Breast pump
  • Storage containers
  • Indelible pen
  • Cooler with freezer pack
  • Cup
  • Warm water
  • Refrigerator
  • Freezer


  • For safety, if you aren't sure of the milk's freshness and it smells a little off -- toss it.


  • Breastfeeding Answer Book; La Leche League International; Revised Edition p 212-215
  • Texas Department of Health: Tips for Nursing Mothers -- Working and Breastfeeding
  • Medela: Breastmilk Collection and Storage

About the Author

Rev. Kathryn Rateliff Barr has taught birth, parenting, vaccinations and alternative medicine classes since 1994. She is a pastoral family counselor and has parented birth, step, adopted and foster children. She holds bachelor's degrees in English and history from Centenary College of Louisiana. Studies include midwifery, naturopathy and other alternative therapies.

Photo Credits

  • BananaStock/BananaStock/Getty Images