FIFO for breast milk: rotate your stash so nothing expires

Most wasted breast milk never went bad. It sat at the back of the freezer while newer bags got used from the front, until one day its date was past the estimated limit. First in, first out — FIFO — is the habit that prevents that, and it takes one rule and one weekly look.

What is FIFO for breast milk?

First in, first out: the milk that went into storage first is the milk that comes out first. Warehouses run on it, and so does a good freezer stash. The point isn't neatness — it's that every bag gets used well inside its estimated window instead of racing the clock at the end. Per the CDC, frozen milk is best within about 6 months, with up to 12 acceptable; refrigerated milk within 4 days; thawed milk within 24 hours of thawing. FIFO keeps you far from all three limits.

What's the right use-first order?

"Oldest first" is only half the answer, because a stash isn't all frozen. At any moment you may have a thawed bag in the fridge, a fresh bag from this morning, and forty frozen bricks. The order that wastes least is whichever clock runs out soonest:

That's the order Milkloft computes for its "use this first" answer: thawed bags by soonest limit, then by earliest estimated expiration, then by oldest expression date. It's also the order a caregiver can follow from a sticky note: "bottle in the fridge door first, then the bag marked Tuesday, then the oldest brick in the freezer bin."

How do I rotate the stash weekly?

1. Pick a rotation day — the day you already restock, say Sunday night.
2. Look at the front of each freezer bin and note the oldest date. If it's within a month or two of its estimated limit, it comes out this week.
3. Swap one for one. If you froze three bags this week, thaw the three oldest for the coming days. The stash keeps its size; its dates move forward.
4. Move tomorrow's bag to the fridge the night before — thawed in the fridge, it has 24 hours from fully thawed (CDC), which is plenty for the next day's bottles.
5. Add new bags to the back. This is the whole system. The moment a new bag lands at the front, FIFO is broken.

On a workday rhythm, this is what "today you pump what your baby drinks tomorrow" looks like in the freezer: today's pumped milk goes to the back; tomorrow's bottles come from the front.

When does the oldest bag actually expire?

Enter the oldest bag's expression date and pick your guideline. The estimated limit — and the row that produced it — tells you whether this week's rotation is comfortable or overdue.

What if a bag is past the 6 months?

The CDC's freezer row reads "about 6 months is best; up to 12 months is acceptable"; the ABM's reads "6 months optimal; 12 months acceptable". So a 7-month bag is inside the outer bound, not past a hard line — but "acceptable" is the guideline's word, not a promise, and neither of these numbers knows how many times your freezer door opened. If a bag is a judgment call, ask your pediatrician or an IBCLC. And if you find yourself with several bags at 10 or 11 months, that's a sign the stash is bigger than the rotation, not that anything went wrong — thaw more, freeze less for a while.

Why does FIFO break down without help?

Because it depends on reading dates. Two freezers, a Sharpie that smeared, a partner who put the new bags at the front, a thawed bag whose "finished thawing" time nobody wrote down: any one of those, and "oldest first" turns into "whichever I grabbed". The rule is easy. The bookkeeping is what fails at 3 AM.

Milkloft does the bookkeeping. Every bag carries its expression date, its location and an estimated expiration from the guideline you chose (CDC by default — editable, with the source shown), and the home screen gives one FIFO answer across every fridge and freezer: "Use the Aug 16 bag first." Thawed bags jump the queue automatically, and a nudge asks you to confirm when a bag in the fridge is actually liquid, because that's when its 24-hour clock is meant to start.