If you’re in the newborn haze (hi, welcome, you’re doing amazing), remembering anything beyond your own name can feel like a stretch. So here’s your no-stress, evidence-based cheat sheet for breast milk storage guidelines—all aligned with NHS and UNICEF Baby Friendly Initiative (2025) recommendations.

Think of this as your screenshot-and-go guide for 2am pump sessions when your brain is operating on fumes.

How to Store Breast Milk Safely:

Room temperature (up to 25°C): Up to 4 hours

Perfect for freshly pumped milk if you’re planning to use it soon.

(Tip: if the room is warmer than 25°C, use the fridge.)

Fridge (≤ 4°C): Up to 5 days

Store breast milk at the back of the fridge, not in the door.

Why? The temperature is steadier back there, especially with all the opening and closing.

Freezer (−18°C or colder): Up to 6 months

Breast milk can be frozen for longer in a deep freezer, but 6 months is the gold standard for maintaining nutrients.

Defrosted milk:

• In the fridge: Use within 24 hours

• Once warmed or left at room temp: Use immediately

• Once baby has started the bottle: Discard after 1 hour

(Bacteria from baby’s mouth gets into the milk — very normal, just not reusable.)

Never refreeze thawed milk.

Once it’s thawed, it’s committed.

Extra Tips to Make Your Pumping Life Easier

1. Label everything

Write the date and time pumped on each container — your future, sleep-deprived self will thank you. Breast milk naturally changes over the day: milk expressed at night contains higher levels of melatonin, while morning milk tends to have more alerting hormones. Some parents like to roughly match milk to the time of day it was pumped where possible, but it’s absolutely not essential. Even a simple AM or PM label can be helpful — and all breast milk is beneficial, whenever it’s given.

2. Use smaller portions

Freezing milk in 60–120ml portions reduces waste when baby only wants a little.

3. Batch your pumped milk

A lot of mums swear by the pitcher method. This involves collecting all pumped milk from the same day into one clean container (or pitcher) in the fridge, then portioning and freezing it in one go — often at night.

Why people like it:

• Uses fewer storage bags
• Less mess and less decanting
• Keeps milk at a consistent temperature before combining (safer)

• Makes batch-freezing quicker and simpler

If you’re combining milk from different pumping sessions, make sure they’re the same temperature first — for example, chill freshly pumped milk in the fridge before adding it to already-cooled milk.

As always, do what feels manageable for you. The “best” system is the one that fits into real life and actually gets used.

4. Thaw milk safely

Move it to the fridge overnight, or place the sealed container in warm water.

Avoid microwaves — they can create hot spots and damage nutrients.

5. Prioritise oldest milk first

Think: first in, first out.

This is the entire evidence-based foundation of safe breast milk storage — simple, doable, and newborn-brain friendly.

6. Lay storage bags flat to freeze

This will make them easier to stack in the freezer and save you some space if things are tight (especially with all the pre-baby batch cooking). 

Why I Made This Guide

Because postpartum is already a lot, and remembering exact fridge temperatures shouldn’t be the thing that breaks you. If these numbers don’t naturally stick in your head, that’s… normal. Truly. Save this, pin it, share it, stick it on your fridge. Whatever makes life easier.

A Little Milk-It Moment

If you’re pumping, breastfeeding, combo feeding — or just trying your best — you deserve something that feels good.

Milk it cookies are:

• Bakery-style lactation cookies
•  Made with ingredients traditionally used to support milk supply (oats, flaxseed, brewer's yeast and fenugreek)
• Freshly baked in small batches every week
• Delivered UK-wide
• A gorgeous gift for yourself or a new mum you love

Because feeding a baby is hard enough — your snacks shouldn’t be. Order yours here.

Want more support? Head to our Breastfeeding Support Hub for practical guides, gentle advice, and tools to make this stage feel a little lighter.

Written by Mel Brittner: doula and postpartum nutrition consultant