Safe Storage of Breast Milk

By following safe preparation and storage techniques, nursing mothers and caretakers of breastfed children can maintain a high quality of expressed breast milk and the health of the baby.

Safely Preparing and Storing Expressed Breast Milk

Be sure to wash your hands before expressing or handling breast milk
When collecting breast milk, be sure to store it in clean containers such as screw cap bottles, hard plastic cups with tight lids, or heavy-duty bags that fit directly into bottles. Avoid using ordinary plastic storage bags or formula bottle bags, ask these can easily leak or spill.
If delivering breast milk to a child care provider, clearly label the container with the child’s name and date.
Clearly label milk with the date it was expressed to facilitate using the oldest milk first.
Do not add fresh milk to already frozen breast milk within a storage container. It is best not to mix the two.
Do not save milk from a used bottle for use at another feeding.
When filling a container for storage, leave an inch of space at the top to allow the breast milk to expand as it freezes.
Keep frozen breast milk in the middle of the freezer away from the sides where the temperature can fluctuate. You do not want to partially thaw breast milk since it cannot be refrozen.

Safely Thawing and Warming Breast Milk

As time permits, thaw frozen breast milk by transferring it to the refrigerator for thawing or by swirling the frozen container in a bowl of warm water.
Avoid using microwaves to thaw or heat bottles of breast milk

Microwaves do not heat liquids evenly. Uneven heating could easily scald a baby or damage breast milk.
Bottles may explode if left in the microwave too long.
Excess heat can destroy the nutrient quality of the expressed breast milk.

Do not bring the temperature of breast milk to boiling point.
Gently swirl breast milk before testing the temperature in order to evenly distribute heat.
Avoid shaking vigorously as it could damage some of the live components of breast milk.
Previously frozen milk that has been thawed can be kept in the refrigerator for up to 24 hours and on the countertop for 1 - 2 hours
Once thawed, breast milk should not be placed in the freezer again.

Types of Storage Containers

Refrigerated or frozen breast milk may be stored in

Hard-sided plastic or glass containers with well-fitting tops
BPA free containers with well-fitting tops
Freezer bags designed for storing breast milk

Breast Milk Temperature and Duration


Location	Temperature	Duration	Comments
Countertop, table	Room temperature (up to 77°F or 25°C)	4 hours	Containers should be covered and kept as cool as possible; covering the container with a cool towel may keep the milk cooler.
Insulated cooler bag	5-39°F or -15-4°C	24 hours	Keep ice packs in contact with milk containers at all times. Limit opening the cooler bag.
Refrigerator	40°F or 4°C	4 days	Store milk in the back of the main body of the refrigerator.
Freezer
Freezer compartment of a refrigerator	5°F or -15°C	2 weeks	Store milk toward the back of the freezer where the temperature is the most constant. Milk stored for a longer duration in the freezer may cause lipids in the breast milk to degrade resulting in lower quality
Freezer compartment of a refrigerator with separate doors	0°F or -18°C	3-6 Months
Chest or upright deep freezer	-4°F or -20°C	6-12 months

Source: Centers for Disease Control and Prevention