Breastmilk Storage Basics

From labeling to refrigeration to freezing, we’ve got you covered with everything you need to know about storing milk safely and having it ready when your baby is hungry. Note: These guidelines are for healthy, full-term babies.

mom getting ready to pump

When storing your breastmilk, whether you put it into a glass or plastic bottle or into a milk storage bag is really just a matter of preference. Whichever container you choose, follow these guidelines for safe breastmilk storage:

  • Wash your hands, and find a clean surface area to prepare your milk for storage.
  • Clearly label your container with the date and the ounces of breastmilk it contains. Labeling with the date and ounces will help you to use the oldest milk first and to prevent waste by only pulling out what your baby needs for that day or that feeding.
  • Store frozen milk in the amounts your baby typically eats in a feeding. For example, if your baby is taking 4- to 6-ounce bottles, store your milk in 2-, 4- or 6-ounce increments.
  • Do not fill a milk storage bag beyond the recommended amount. Overfilling storage bags can cause the bag to leak or even break because the milk expands as it freezes.
  • Know that it’s OK to combine milk from different pumping sessions within the same day as long as they are both the same temperature. For example, you can combine refrigerated milk from 2 separate pumping sessions or room temperature milk from 2 separate pumping sessions. Do not combine refrigerated milk and room temperature milk until the room temperature milk is cold.

dad putting expressed milk in fridge

Here are some guidelines for how long your freshly expressed breastmilk will last depending on how you store it:

  • Up to 4 hours at room temperature.
  • 24 hours in a cooler bag with ice packs.
  • Up to 4 days in the refrigerator.
  • 6 months in a freezer or deep freezer (12 months is considered acceptable).

If you notice chilled or frozen milk is separating into layers, don’t worry. It’s normal. Once the milk is warmed, you can swirl the layers back together. Also, don’t panic if your milk varies in color. The color of breastmilk may change depending on what you’re eating or drinking; however, if you are concerned, be sure to speak with a lactation consultant or healthcare provider.

dad swirling bottle of breastmilk

When you’re storing breastmilk, there are some do’s and don’ts the Centers for Disease Control and Prevention recommends in order for expressed breastmilk to be completely healthy for your baby:

  • Never put breastmilk or formula in the microwave because it destroys nutrients and creates hot spots that can burn your baby. Instead, thaw frozen milk in the refrigerator (this will take about 24 hours) or in a cup of lukewarm water.
  • Swirl the milk as it thaws to mix the layers.
  • Do not refreeze milk once you’ve thawed it.
  • Use thawed milk within 24 hours.
  • Once a baby has drunk from a bottle, use the milk within 2 hours. After 2 hours are up, dispose of the excess milk. No one wants to waste milk, but it’s better to be safe than sorry when it comes to your baby’s health!