Breast Milk Storage: How Long It Keeps, and When to Throw It Out

Is this milk still good?

Tell it what the milk is, when that happened and where it is being kept. Milk the baby has already drunk from is a different question from milk still in the bottle, so the timer asks first.

The windows, and the one thing they assume

Freshly expressed milk keeps about four hours at room temperature, a day in a cool bag with ice packs, four days in the fridge, and six months in a deep freezer. Those are the figures every guideline carries — and every one of them is quoted for a room at or below 25 degrees.

That qualifier does most of the work in India. A kitchen at 33 degrees in May is not the room those hours were measured in, and the practical window on the counter is closer to two hours. The timer asks whether the room is hot and halves the counter figure when it is; the fridge and freezer numbers do not change, because those appliances hold their own temperature.

Keep milk at the back of the fridge, not in the door. The door is the warmest part and it swings through room temperature every time someone opens it.

Which freezer you have changes the answer

Most charts have one freezer row, and Indian kitchens have three different appliances. A freezer compartment inside a single-door fridge defrosts a little every time the door opens: two weeks. A freezer with its own door, in a double-door fridge: about three months. A deep freezer holding minus 18 degrees: six months, and up to a year if it is never opened.

Freeze in small amounts — 60 to 120 ml — because thawed milk that is not used has to go, and nobody wants to pour away 200 ml. Leave a finger's width at the top: milk expands as it freezes. Label every bag with the date, in pen that survives a freezer.

Milk the baby has already drunk from

Once a baby has fed from the bottle, bacteria from their mouth are in the milk, and the clock is two hours from the end of that feed — wherever you keep it. It does not go back in the fridge, and a cool bag does not extend it.

The same two hours apply to milk you warmed and then did not use. This is the cautious reading of the guidance and we take it deliberately: the alternative saves a small amount of milk and risks a gut infection in a newborn.

Thawing, warming and the soapy smell

Thaw in the fridge overnight, or under running water that starts cool and warms up. Never in the microwave: it heats unevenly, leaves scalding pockets and damages some of what makes breast milk worth the trouble. Thawed milk keeps 24 hours in the fridge and two hours out, and is never refrozen.

Milk that smells soapy or metallic after freezing is usually high lipase, not spoiled milk. Lipase breaks down fat in storage and changes the smell without making the milk unsafe; many babies take it anyway. Spoiled milk smells sour in a way you will not mistake, and does not mix back together when swirled.

Fresh milk can be added to a cold bag already in the fridge — cool the new milk in the fridge first, so warm milk does not rewarm what is already there. The whole batch then keeps from the time the OLDEST milk in it was expressed.

Common questions