Breast milk is a dynamic and complex fluid, providing tailored nutrition and immune support for infants. Proper storage of expressed breast milk is important to maintain its beneficial properties and protect the baby’s health.
Room Temperature Storage
Freshly expressed breast milk can be safely kept at room temperature, 77°F (25°C) or colder, for a limited time. It is recommended to use or store this milk within four hours. Chilling the milk as soon as possible is advised to preserve its quality. Warmer environments may reduce the safe storage time.
Refrigerated and Frozen Storage
For longer storage, breast milk should be refrigerated or frozen promptly after expression. Refrigerated breast milk, stored at 40°F (4°C) or below, is best used within four days. Placing containers in the back of the refrigerator, rather than the door, helps maintain a consistent, colder temperature. For freezing, breast milk can be stored in a standard freezer (0°F or -18°C) for up to nine months; six months is ideal for best quality. Deep freezers at -4°F (-20°C) or colder can extend this duration to up to twelve months.
When preparing milk for freezing, use clean, food-grade containers made of glass or hard plastic that are BPA-free, or specialized breast milk storage bags. Store milk in small portions, typically 2 to 4 ounces, to avoid waste and allow for expansion during freezing. Leave about an inch of space at the top of the container to accommodate this expansion.
Handling Previously Stored Milk
Once breast milk has been stored, handle it carefully before feeding. Frozen milk should be thawed safely by placing it in the refrigerator overnight, or by holding the container under warm running water or in a bowl of warm water. Never thaw or warm breast milk using a microwave, as this creates hot spots and diminishes nutrient content. After thawing in the refrigerator, the milk should be used within 24 hours.
Thawed milk that has been brought to room temperature or warmed should be used within two hours. Never refreeze breast milk once it has thawed. If a baby does not finish a bottle of milk, any remaining milk should be used within two hours or discarded to prevent bacterial growth.