How long can you safely store breastmilk?

By Alison Heyerdahl

Pumping breastmilk is no easy task, and for mothers who are returning to work, heading back to the gym, or who just need one full night’s sleep, preserving and correctly storing their liquid-gold is of utmost importance.  

Expressed breastmilk retains most of its healthcare benefits and is a better option than formula-feeding a baby if possible for the mother, but it is important to ensure that correct storage and hygiene guidelines are followed. 

How long can breastmilk be stored?

Freshly expressed breastmilk can be stored at room temperature for 4 hours (as long as temperatures aren’t too high) and stored in the fridge for up to 4 to 6 days, depending on how cold the fridge is.   If an insulated cooler with ice packs is used for storing breastmilk, it is advisable to use the milk within 1 day.  Long-term, breastmilk can be successfully stored in a freezer for up to 12 months, however, it is optimal to use the milk within 6 months.  

It must be remembered that the longer breastmilk is stored (whether in a fridge or a freezer), the more vitamin C is lost from the milk.  Furthermore, our bodies are so intelligent that the constituents of the mother’s breastmilk adapt to the changing needs of the baby.  For example, after birth, breastmilk contains high levels of colostrum, a strong immune booster, important for killing viruses and bacteria.  Later on, breastmilk contains more fat and carbohydrates to ensure that the baby has enough energy for the new activities he will perform.  As a result, breastmilk that was expressed months earlier may not be sufficient for the baby’s current stage of development.  

Breastmilk Refrigeration Storage Guidelines

• Before expressing, ensure that hygiene measures are taken.  Handwashing and washing storage containers that will hold the breastmilk is important.  Labeling the containers with the child’s name and the date the breastmilk was expressed helps inform which milk should be used first, especially if it is being given to a caregiver.

• Use BPA-free baby bottles or bags to store the milk.  If baby bottles are being used, remove the nipple to avoid air going into the milk container. 

• Store the breastmilk in small batches to avoid waste.  The containers should ideally hold 2 – 4 ounces of breastmilk.

• Refrigerate the breastmilk as soon as possible after expressing it.  Although breastmilk can remain at room temperature (77°F or 25°C) for up to 4 hours, it is best to refrigerate it as soon as possible.

• Store breastmilk at the back of the refrigerator where it is the coldest.  This ensures that the temperature remains consistent.

• It is best to use refrigerated breastmilk within 4 days of expression, although it can be stored for up to 6 days.  If it looks like the breastmilk will not be used in time, consider freezing the milk.  Frozen milk should be stored at the back of the freezer where temperatures are consistent. 

How can milk be warmed up after being in the refrigerator?

Try and avoid microwaving the milk, as it can lead to scalding the baby, overheating the milk, and destroying the protective antibodies present in the milk.  Place the container with the breastmilk into a bowl of warm water and allow it to return to room temperature before feeding the baby.   Gently swirl the bottle or bag to mix any separated fat.  

Some mothers report that their breastmilk smells different after it has been refrigerated.  This is because an enzyme called lipase breaks down into fatty acids when cooled down.  If the hygiene and refrigeration guidelines have been correctly followed, this should not be a concern; the milk is safe for the baby’s consumption.  Always use breastmilk within 2 hours of warming, and never refreeze or refrigerate the milk once it has been warmed.