How to Store Breast Milk and Formula Safely, According to the CDC

How to Store Breast Milk and Formula Safely, According to the CDC

It is important to follow proper guidance when it comes to storing, thawing and serving breast milk or formula to your baby, but can also become quite confusing as the recommendations differ depending on the type of milk you are using!

Find out what the CDC advises on safely storing, thawing, and serving breast milk (including freshly pumped milk, refrigerated milk and thawed milk), as well as infant formula.


Storage Guidelines for Pumped Breast Milk

  • Freshly expressed breast milk can be left unrefrigerated for up to 4 hours. 
  • Pumped breast milk can be kept in a refrigerator for up to 4 days.
  • Breast milk can be frozen for up to 12 months but is best for consumption within 6 months.

Storage Guidelines for Thawed Breast Milk

  • Thawed breast milk can be unrefrigerated for 1-2 hours.
  • Previously frozen breast milk is safe in a refrigerator for 1 day.
  • Breast milk should never be refrozen once thawed.

Any breast milk leftover from a feeding should be consumed within 2 hours after the initial feeding.

The Safest Containers for Storing Breast Milk

Breast milk should be stored in clean, capped, food-grade containers. This includes plastic containers, glass containers, or breast milk storage bags.

You should not store breast milk in plastic bags made for general household use because these could introduce harmful bacteria into your breast milk. 

When choosing a container for breast milk storage, you want to avoid any containers made with the chemical bisphenol A (BPA). 

Why is storing my breast milk in a container made with BPA harmful?

BPA is a chemical found in polycarbonate plastics and epoxy resins that has been used in food storage since the 1950s. 

According to the Mayo Clinic, BPA present in containers’ materials can leak into food or beverages stored in these containers. BPA can lead to adverse health effects on the brain and prostate gland of fetuses, infants, and children. In addition, BPA could alter children’s behaviors. Some studies have also uncovered a potential link between BPA exposure and higher blood pressure, type 2 diabetes, as well as cardiovascular diseases.

6 Tips for Properly Freezing Breast Milk for Storage

  1. Label all containers of breast milk with the date you pumped. You can use a permanent marker to write directly on breast milk storage bags, or put a piece of tape on a storage container and write the date on top of the tape.
  2. Keep one inch of room in your breast milk storage containers for the liquid to expand upon freezing.
  3. Use your oldest milk first when thawing breast milk. Remember to use all frozen breast milk within one year of expressing, but ideally within 6 months of expressing.
  4. Place your breast milk storage bag into a clean, sterilized cup when transferring expressed milk from your pump. This way if any breast milk leaks or spills out of the bag, you can safely pour that milk into the storage bag without wasting ounces.
  5. Place your freshly expressed milk in storage bags on a flat surface in your freezer. You can use a half-sheet tray or place a plate in your freezer for stabilization. Once your milk is frozen solid, it can be more compactly stored in an upright position.
  6. Keep smaller portions of frozen milk on hand for topping-off bottles. Store 2-ounce portions for when your baby is especially hungry and wants to keep eating after their normal feed. This minimizes any potential waste of unused breast milk.

How to Use Undrinkable Breast Milk

Don't discard (undrinkable) breast milk! Those precious ounces are worth their weight in gold even if you can't feed it to your child after the milk goes bad, unused, or becomes expired milk.

Pour undrinkable breast milk into a milk bath, or use it to address any of the following issues: 

  • diaper rashes
  • cradle cap
  • sunburns
  • cracked nipples
  • baby acne
  • eczema
  • clogged tear ducts 

Prepared Infant Formula Storage Guidelines

  • Any prepared formula should be used within 1 hour of when a feeding begins.

  • Prepared infant formula (in a clean, unused bottle) can be stored on a countertop for up to 2 hours.

  • Prepared infant formula (in a clean, unused bottle) can be kept in the refrigerator for up to 1 day. 

Unprepared, Dry Infant Formula Storage Guidelines 

  • Unprepared infant formula should be stored in a cool, dry place.

  • Do not store dry formula in a refrigerator.

  • Never leave dry formula in a vehicle, garage, or outdoors for storage.

  • After removing the seal on a container, write the date you first opened it and use it within the window of time recommended on the package (typically within 1 month of opening.)

  • Use all formula before the “Use By” date on the container.

Why do you need to discard prepared infant formula after 2 hours or within 1 hour of feeding?

Even though powdered infant formula has been manufactured to meet hygiene standards, it is not a sterile product. This means that it is possible for pathogens, such as harmful bacteria, could be present which would make your baby ill. 

Experts from the World Health Organization (WHO) and the Food and Agriculture Organization of the United Nations (FAO) suggested that bacteria can contaminate powdered infant formula during the manufacturing and the preparation stages. In some cases, bacteria such as E. sakazakii and Salmonella enterica have led to severe illness and even deaths in infants. Since current manufacturing technology does not permit the complete elimination of germs from powdered infant formula, it is important for you to do your part to minimize the risks of formula contamination by properly handling and storing formula for your baby.

How to Properly Handle Prepared Infant Formula and Prevent Formula Contamination

Avoid storing prepared formula at room temperature, which would promote the rapid growth of E. sakazakii or Salmonella. To maximally prohibit bacterial growth, keep bottles refrigerated at less than 41 °F (5 °C).

Always use clean utensils when handling prepared infant formula. Dirty utensils such as spoons, blenders, or bottle parts have bacteria present on their surfaces and can contaminate the formula.

Be careful of the bacteria present in the bottle-preparation environment such as countertops. Unwashed hands, dirty table surfaces, and / or  untreated water can all be sources of contamination. 

Is my baby going to get sick from formula?

Parents who follow all recommended safety measures for preparing, storing, and discarding formula should not feel that formula is an unsafe choice for their child. Sanitizing bottles with a heated drying cycle in your dishwasher and boiling or steaming bottle parts are some additional steps you can take to prevent contamination of formula. 

However, there are some groups of babies that are at higher risk of infection or illness from spoiled formula. Parents of these children should carefully follow all best practices for formula storage.

According to the WHO, preterm infants and low-birth-weight infants are at greatest risk of E. sakazakii infection. Moreover, neonates and babies 0-2 month-old are generally at high risk.  Immunocompromised infants, such as those of HIV-positive mothers, are also at high risk but may specifically require formula feeding to avoid getting infected by HIV via breast milk. 

7 Bottle Tips to Follow for Safe Breast Milk and Formula Handling and Storage

1. Wash your hands.

Before mixing up a bottle, it is vital that you wash your hands thoroughly with warm water and soap. Touching a clean bottle with dirty hands can unintentionally introduce nasty germs to your baby.

2. Heat gently.

Never microwave breast milk or formula – this heats bottles unevenly, which can create hot spots in the liquid and potentially damage your breast milk. Instead, place a bottle with cold breast milk or formula in a cup of warm water for several minutes to heat it through.

3. Check the temperature.

Drip several drops of the bottle’s liquid onto your wrist before giving it to your baby. A bottle’s contents should feel lukewarm to the touch, rather than hot or cold.

4. Always hold the bottle.

It might be tempting to prop a bottle up during a feed – but this puts your baby in a dangerous situation. Bottle propping can lead to choking, aspiration, ear infections, and overfeeding. Always hold a bottle for your baby until they are old enough to grip it themselves.

5. Discard breast milk appropriately.

Any leftover breast milk in a bottle should be used or discarded within 2 hours. However, if you find yourself frequently throwing away leftover milk, offer one main bottle with a reserve of 1-2 ounces in a secondary bottle for times when your baby is still hungry.

6. Discard formula appropriately.

Use prepared formula within 2 hours of preparation and within 1 hour from when a feeding begins. Throw out any formula that is left in a bottle after a feed. Your baby’s saliva can promote bacterial growth in the leftover infant formula.

7. Clean, clean, clean.

Separate all bottle parts (nipples, caps, rings, and valves) and rinse under running water. Wash by hand or in a dishwasher. Use a heated drying cycle in the dishwasher to sanitize, or sanitize hand-washed bottles in boiling water or steamer bags.