How long does expressed breast milk keep?

How long you can safely keep expressed breast milk depends on how you store it. Keep in mind these general guidelines:

• Room temperature. You can keep freshly expressed breast milk at room temperature for up to six hours. But it's best to use or store the breast milk within four hours, especially if the room is warm.
• Insulated cooler. You can keep freshly expressed breast milk in an insulated cooler with ice packs for up to one day.
• Refrigerator. You can keep freshly expressed breast milk in the back of the refrigerator for up to four days. If you don't plan to use it within four days, freeze it right after pumping.
• Deep freezer. You can store freshly expressed breast milk in the back of a deep freezer for up to 12 months. But it's best to use the frozen milk within six months.

Keep in mind that research suggests 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 your breast milk changes to meet your baby's needs. Breast milk expressed when a baby is a newborn won't meet the baby's needs when the baby is a few months older.