Breast milk provides essential nutrients and antibodies. Proper storage and handling are important to maintain its nutritional quality, prevent bacterial growth, and ensure it remains safe for the baby.
Room Temperature Guidelines
Freshly expressed breast milk can remain at room temperature, specifically 77°F (25°C) or colder, for up to four hours. While some sources suggest up to six hours, using or storing the milk within four hours is generally recommended, particularly if the room is warm. This timeframe helps preserve the milk’s beneficial properties and limits bacterial proliferation.
Factors such as the ambient temperature of the room directly influence how long breast milk can safely sit out. In warmer environments, it is advisable to use or refrigerate the milk sooner to prevent rapid bacterial growth. If freshly expressed milk is not intended for immediate use, it should be refrigerated or frozen promptly to maintain its quality.
It is important to differentiate between freshly expressed milk and milk that has been previously refrigerated or frozen. Once breast milk has been thawed or warmed, its time at room temperature is significantly reduced. Such milk should be used within a shorter window, typically two hours, to ensure safety.
Refrigeration and Freezing
Storing breast milk in a refrigerator helps preserve its quality for several days. Freshly expressed breast milk can be kept in the back of the refrigerator, where temperatures are most stable, for up to four days at 40°F (4°C) or colder. Storing milk in smaller portions, such as 2 to 4 ounces, can help prevent waste.
For longer storage, freezing breast milk is an effective method. In a standard freezer (0°F or -18°C), breast milk can be stored for about six months, though it can remain acceptable for up to twelve months. For optimal quality, it is recommended to use the milk within six months.
When freezing, leave about an inch of space at the top of the container, as breast milk expands when it freezes. Clean, food-grade containers made of glass or hard plastic without BPA, or special breast milk storage bags, are suitable for storage. Storing milk in the back of the freezer or refrigerator, rather than in the door, minimizes temperature fluctuations. For temporary transport, an insulated cooler with ice packs can keep freshly expressed milk safe for up to 24 hours.
Safe Handling and Usage
Safe thawing methods are important to maintain the quality of stored breast milk. Frozen breast milk can be thawed slowly in the refrigerator overnight, typically taking about 12 hours. Once fully thawed in the refrigerator, it should be used within 24 hours. Alternatively, frozen milk can be thawed more quickly by placing the container under cool or lukewarm running water, or in a bowl of warm water.
Rewarming breast milk is often a personal preference, as some babies accept cold or room-temperature milk. If warming, a warm water bath or bottle warmer is recommended. The milk should feel warm, not hot, when tested on the wrist. Microwaving breast milk is not advised, as it can create hot spots that may burn a baby’s mouth and can destroy nutrients.
Previously thawed breast milk should never be refrozen. After a feeding, any leftover milk in the bottle should be discarded within two hours to prevent bacterial growth from the baby’s mouth. Signs of spoiled milk include a sour or rancid odor, a chunky consistency that does not mix when swirled, or a sour taste.