Pumping
Storing breast milk
How long pumped milk keeps at room temperature, in the fridge and in the freezer, and how to thaw and warm it.
Pumped milk keeps well when it's stored cold and handled cleanly. The times below are from the CDC. The NHS uses slightly different times, shown further down. Pick one source and stick with it.
How long it keeps
| Where | How long |
|---|---|
| Room temperature, 77°F (25°C) or colder | up to 4 hours |
| Insulated cooler with frozen ice packs | up to 24 hours |
| Refrigerator | up to 4 days |
| Freezer | about 6 months is best, up to 12 months is acceptable |
| Thawed in the fridge | use within 24 hours |
| Warmed or brought to room temperature | use within 2 hours |
| Left in the bottle after a feed | use within 2 hours, then throw it away |
If you won't use fresh milk within 4 days, freeze it right away. Never refreeze milk that's been thawed.
The NHS times
- Fridge at 4°C or colder: up to 8 days, at the back.
- Fridge warmer than that, or unsure: use within 3 days.
- Ice compartment of a fridge: up to 2 weeks.
- Freezer at −18°C or colder: up to 6 months.
- After your baby drinks from a bottle, use the rest within 1 hour, then throw it away.
Storing it well
- Wash your hands well before expressing or handling milk.
- Use breast milk storage bags or clean, food-grade glass or plastic containers with tight lids.
- Label each one with the date it was expressed.
- Freeze small amounts, 2 to 4 oz (60 to 120 ml) or one feed's worth, to avoid waste.
- Leave about 1 inch (2.5 cm) at the top, since milk expands as it freezes.
- Store it toward the back, away from the door, where the temperature stays steadier.
- Use the oldest milk first.
Thawing and warming
- Thaw overnight in the fridge, in a bowl of warm water, or under lukewarm running water.
- Breast milk doesn't need warming. It can be served cold or at room temperature.
- To warm it, set the sealed container in warm water for a few minutes.
- Never thaw or heat milk in a microwave. It creates hot spots that can burn your baby's mouth.
- Swirl to mix in the fat, which often separates.
- Test a few drops on your wrist before feeding.
Cleaning pump parts
Clean parts that touch milk soon after each use and let them air-dry. "Pumping basics" has the full steps.
Premature or sick babies
If your baby is in the hospital, ask the staff how to store milk for them.