In the past, we were unaware of the properties in breast milk which protect it from bacteria. Because of our new awareness, the guidelines for storage has increased significantly. One study found no increase in bacteria levels in breast milk stored at room temperature for 10 hours vs. refrigerated for the same time. A more recent study showed after 8 days in the refrigerator, there was actually a drop in the bacterial levels of breast milk!
Storing milk in 2 to 4 ounce containers minimizes waste and allows for quicker thawing of frozen milk. On average, most breastfed babies take between 2 to 4 ounces of milk, 8 to 12 times per day. (Because of a decreased and more organized heart rate of breastfed babies, they expend less energy as compared to formula fed babies. As a result, the amount of calories consumed is about 25% less).
At room temperature:
- Term colostrum (first 6 days) – 12 hours
- Mature milk
- 60° F– 12 hours
- 66° to 72° F – 10 hours
- 79° F – 4 to 6 hours
- Mature milk
- 32° F to 39° F – 8 days
- Freezer compartment inside refrigerator - 2 weeks
- Self-contained freezer unit of a refrigerator - 3 to 4 months
- Separate deep freeze - 6 months or longer (up to a year)
Researchers conclude that if milk is to be used within 8 days, it is better to refrigerate rather than freeze. Anti-microbial qualities of human milk are better preserved by refrigeration.