Breast milk provides comprehensive nutrition and protective factors for infants, supporting their growth and development. It contains essential sugars, proteins, fats, vitamins, and minerals, along with antibodies and immune-boosting elements that help protect against infections and illnesses.
Using Warmed Breast Milk
Once breast milk is warmed, it should be used promptly to maintain its safety and quality. Warmed breast milk should be consumed within two hours of reaching room temperature. If a baby begins feeding from a bottle, any milk remaining should be used within one hour from the start of the feeding.
A baby’s saliva can introduce bacteria into the milk, which multiplies quickly at warmer temperatures. Therefore, any leftover milk in the bottle after a feeding should be discarded after the one-hour window. Re-refrigerating or re-warming partially consumed milk is not recommended due to the increased risk of bacterial growth.
Proper Warming Methods
Placing a sealed container of breast milk in a bowl of warm water or holding it under warm, running tap water for a few minutes are effective warming methods. Specialized bottle warmers can also be used, provided they heat the milk gently and evenly.
Avoid using a microwave to warm breast milk. Microwaves create uneven heating, resulting in “hot spots” that could burn a baby’s mouth. Microwaving may also diminish some of the beneficial nutrients and immune components present in the milk. Before offering warmed milk, always test its temperature by placing a few drops on the wrist; it should feel lukewarm, not hot.
Storing Unwarmed Breast Milk
Freshly expressed breast milk can be stored at room temperature (around 77°F or colder) for up to four hours. For longer storage, it can be kept in the refrigerator at 40°F or colder for up to four days.
For extended preservation, breast milk can be frozen at 0°F or colder. It is best to use frozen milk within six months, though it is acceptable for up to twelve months. Once frozen milk has been thawed in the refrigerator, it should be used within 24 hours. Thawed milk should never be refrozen.
Recognizing Spoiled Breast Milk
Fresh breast milk typically has a mild, slightly sweet scent and an ivory-white color. If the milk develops a distinctly sour, rancid, or fishy odor, it has likely spoiled.
While breast milk naturally separates into layers when stored, it should mix back together smoothly with a gentle swirl. If the milk appears chunky, curdled, or does not reintegrate after swirling, it may be spoiled. Tasting the milk can also provide an indication; spoiled breast milk will have an overtly sour or unpleasant taste. If there is any doubt about the milk’s freshness, it is safest to discard it.