Storing Breast Milk

It is important to know the guidelines for storing breast milk properly so that you always give your baby fresh milk. Any container used to store milk should be clean and sterile. Always try to leave an inch or so from the milk to the top of the container since frozen milk expands. After pumping your milk, it is helpful to label the storage container. Always use the oldest dated milk first. Colostrum, or the first milk expressed in the first few days after delivery, can be stored at room temperature for up to 12 hours. Mature milk, or breast milk that comes in six days after the birth of your baby can be stored in the following ways:

At Room Temperature:

• At 60 degrees Fahrenheit for 24 hours (15.5 Celcius)
• At 66-72 degrees Fahrenheit for 10 hours (19-22 Celcius)
• At 79 degrees Fahrenheit for 4-6 hours (26 Celcius)
• At 86-100 degrees Fahrenheit for 4 hours (30-37 Celcius)

In the Refrigerator:

• At 32-39 degrees Fahrenheit for up to 8 days (0-4 Celcius)

In the Freezer*:

• In a freezer compartment contained within the refrigerator for up to 2 weeks
• In a self-contained freezer, either on top of or on the side of the refrigerator for 3 - 4 months
• In a deep freezer with a constant 0 degrees Fahrenheit for 6 months or longer (-17 Celcius)

*It is helpful to freeze the milk in small amounts, such as 2 to 4 ounce servings, so there is less waste and you can choose the amount of milk depending on the baby's hunger.

Bottles and Containers

You can store breast milk in bottles that fit directly onto your breast pump. After pumping, simply remove the pumping tubing, cover with the bottle lid, label the milk, and put it in the refrigerator. Many breast pump carrying cases also come with built-in, cooler-type compartments for storing ice pack and/or the freshly pumped bottles of milk. If used correctly, these do stay cold enough to leave your pumped milk in until you can get home to store the milk in the refrigerator or freezer.

Research is conflicting about the advantages and disadvantages of storing milk in glass versus plastic. However, glass bottles or containers are best for freezing breast milk because it offers the most protection from contamination. The second choice is clear, hard plastic, and the last choice is the cloudy hard plastic containers. Wait to tighten the caps or lids until the milk is completely frozen.

Storage Bags

If you want to freeze your breast milk in bags, you can purchase storage bags that fit directly onto your breast pump and that are made for freezing milk. They are pre-sterilized, thick, have an area for labeling, and seal easily. After pumping, simply remove the pumping tubing, fold the bag over, making sure all air is out of the bag, and seal it. Make sure to label the bag with the date before freezing. When you want to use the milk, you can cut the storage bag with sterile scissors. If the storage bag has a built-in pouring spout, it is easy to pour the milk into a bottle. Other storage bags can be used in the kind of bottle that uses disposable liners, so there is no need to transfer the milk.

Thawing and Handling Stored Breast Milk

It is normal for stored breast milk to separate in its container into two parts, what looks like cream and then a lighter colored milk. Some human milk also varies in color and can be blueish, yellowish, or brownish. Just gently shake the milk before feeding to mix it back together.

Breast milk doesn't take long to thaw or warm up. Never place a bottle or bag of breast milk in the microwave. Milk doesn't heat uniformly in the microwave, so you won't have control over the temperature and could burn your baby. All you have to do is hold the bottle or frozen bag of milk under cool and then warm water for a few minutes. If warm running water is not available, you can heat up a pan of water on the stove. Remove the pan from the heat and place the container into the warm water. Never warm the container directly on the stove. Shake the milk, then test it on your wrist to see if it's warm enough for your baby.