How long does expressed breast milk keep?

How long you can safely keep expressed breast milk depends on the storage method. Consider these general guidelines for healthy infants:

  • Room temperature. Freshly expressed breast milk can be kept at room temperature for up to six hours. However, use or proper storage within four hours is optimal. If the room is especially warm, the limit is also four hours.
  • Insulated cooler. Freshly expressed breast milk can be stored in an insulated cooler with ice packs for up to one day.
  • Refrigerator. Freshly expressed breast milk can be stored in the back of the refrigerator for up to five days in clean conditions. However, use or freezer storage within three days is optimal.
  • Deep freezer. Freshly expressed breast milk can be stored in the back of a deep freezer for up to 12 months. However, using the frozen milk within six months is optimal.

Keep in mind research suggests that the longer you store breast milk — whether in the refrigerator or in the freezer — the greater the loss of vitamin C in the milk. It's also important to note that breast milk expressed when a baby is a newborn won't as completely meet the same baby's needs when he or she is a few months older. Also, storage guidelines might differ for preterm, sick or hospitalized infants.

How do I thaw frozen breast milk?

Thaw the oldest milk first. Place the frozen container in the refrigerator the night before you intend to use it. You can also gently warm the milk by placing it under warm running water or in a bowl of warm water.

Also, don't heat a frozen bottle in the microwave or very quickly on the stove. Some parts of the milk might be too hot, and others cold. Some research suggests that rapid heating can affect the milk's antibodies.

While further research is needed on whether previously frozen milk that's been thawed can be frozen again and safely used, many experts recommend discarding thawed milk that isn't used within 24 hours.

Does thawed breast milk smell or look different from fresh breast milk?

The color of your breast milk might vary, depending on your diet. Also, thawed breast milk might seem to have a different odor or consistency than freshly expressed milk. It's still safe to feed to your baby. If your baby refuses the thawed milk, it might help to shorten the storage time.

April 07, 2015 See more In-depth