Many breastfeeding moms also end up pumping breast milk to give at a later time. This is sometimes due to supply, work schedule, or personal preference. Whatever the reason, safely storing breast milk for later use is an important step to keeping the milk fresh and healthy for your baby. Although giving fresh breast milk is best, safely stored breastmilk can be given days or months after it is initially collected.
When pumping, expressing, or handling breast milk, the first step should always be washing your hands and cleaning the storage container you will be using (bottle or bags). If you are planning to use the pumped milk immediately, it can remain at room temperature for up to 4 hours and still be safe to give. If an infant starts a feeding but does not complete it, the remaining milk may be refrigerated for 2 hours. The refrigerator is the best place to store milk that will not be given immediately; storing the milk in the back of the fridge will provide the most consistent temperature (fridge temp should be set to about 39 degrees Fahrenheit). Freshly expressed/pumped breast milk can remain in the refrigerator for up to 4 days before discarding it. For longer milk storage, breast milk can be kept in a freezer at 0 degrees Fahrenheit or lower for up to 9 months; if using a deep freezer (temperature -4 degrees or less), it can be stored and used for up to 12 months.
When storing breast milk, do not fill up your container or bag all the way; instead store the milk in smaller quantities, such as 2-4 ounces. This can help decrease unnecessary waste and ensures the container does not break or open if the milk expands while frozen. When thawing or warming up milk, avoid using the microwave, as this can cause inconsistent temperatures that may leave scalds or burns on your baby. A warm water bath or putting the milk under a stream of warm water works well to safely heat the milk. Once frozen milk has been thawed, it can be refrigerated for 24 hours. Breast milk may be given cold and does not necessarily need to be warmed up, although some infants may prefer a warm bottle.
For more information on safe handling and storage of breastmilk, view this article from the CDC and this Healthy Children article!