Proper Human Milk Handling, Storage, and Preparation
We recommend following the CDC guidelines for storing and preparing human milk to keep your breast milk safe and uncontaminated. Cronobacter infections can occur to human milk fed infants, which can come from contaminated pump parts.
Before Pumping
- If using a multi-user pump, clean the countertop, dials and other high touch parts with a disinfectant wipe.
- Wash your hands thoroughly with soap and water for 20 seconds.
- Assemble your clean pump parts, inspecting them for damage and the tubes for mold. If there is mold, discard and replace them.
- Pump your breast milk. For detailed instructions, read Chapter 8 of the Fed Is Best Book.
After Pumping
- Immediately cap the bottle or seal the collection bags, label with the date collected and place in the refrigerator, freezer, or cooler with ice packs. See CDC recommendations for milk storage guidelines.
- Disassemble, clean and sanitize pump kit using the same methods for bottle washing.
- Clean pump kit (the flange, milk collection bottle, and membrane) by washing them in a clean bin used only for pump parts with soap and warm water using a bottle brush to clean the parts thoroughly.
- Dry the pump kit on a clean paper towel or unused clean dish towel.
- Alternatively, you may wash and sanitize your pump parts (fully disassembled) in a dishwasher on the top rack.
- Sanitize your pump kit once daily using a commercially available microwaveable steam bag for sanitizing pump kits, by boiling them in water, or by washing them in the dishwasher using the hottest water setting.
- Make sure to clean and dry your wash basin and brush.
- Clean the countertop with a disinfectant wipe.
Storing Breast Milk After Pumping
- Use only breast milk storage bags or sterilized infant bottles. Leave a little room when filling containers because freezing expands the volume.
- Label the container with the date it was pumped.
- Don’t store breast milk in the door of the refrigerator.
- Freeze milk within 4 days if not used.
- Store your milk bags in chronological order.
- If transporting milk, use an insulated cooler with frozen ice packs for up to 24 hours.
Expert Tip: Preventing Waste by Freezing Different Volumes of Milk
Many parents will pump and store the amount their infant receives for one feed, usually 2–3 ounces of breastmilk per freezer bag. Having a few one ounce bags of breast milk will give you the flexibility of giving your baby a little bit more if they are still hungry after finishing a bottle. It can reduce waste that may occur if they are unable to finish a larger volume bag of thawed breast milk.
Thawing Breast Milk
- Thaw the oldest milk first either:
- overnight in a refrigerator.
- in a container of warm water.
- under warm running water.
- Never thaw breast milk in a microwave.
- Never refreeze breast milk after thawing.
- Never leave breast milk out to thaw on the counter top.
Feeding Thawed Breast Milk
- Breast milk can be fed at room temperature or cold.
- Swirl the breast milk before feeding to mix in the fat.
- If your baby does not finish the bottle, use the leftover milk within 2 hours. After 2 hours, discard the remaining milk.
A Few Facts About Human Milk
Milk varies from yellow to orange in the first 2 weeks and then becomes thin and bluish when mature. A small amount of blood can turn the milk pink, which is safe to feed. Or it can take on a color from food additives or vitamins the mother is consuming.
In rare cases, a bacterial infection called Serratia marcescens can cause bright bubble-gum pink milk. While a baby fed breast milk with S. marcescens may not ingest enough organism to cause illness, improper handling and storage may allow the organism to multiply to sufficient numbers to cause disease, especially for vulnerable infants (e.g. preterm). If you notice this, you should consult with your obstetrician regarding possible need for treatment.
Some mothers will notice that their frozen milk develops an off smell or taste. This is usually due to an enzyme called lipase. If milk is brought to scalding temperature (180º F), it will deactivate lipase and prevent this effect. However, doing so may denature antibodies in your milk and reduce immunological benefits.
Note to mobile users: The following table is best viewed in landscape or horizontal view.
Human Milk Storage Guidelines from the CDC
| Type of Breast Milk | Room temperature 77°F (25°C) | Refrigerator 40°F (4°C) |
Freezer 0°F (–18°C) or colder |
|---|---|---|---|
| Freshly Expressed or Pumped | Up to 4 hours | Up to 4 days | Up to 6 months is best, up to 12 months is acceptable |
| Thawed, Previously Frozen | 1 to 2 hours | Up to 1 day | NEVER refreeze human milk after thawing |
| Leftover from an unfinished bottle | Feed within 2 hours | Do not refrigerate | Do not refreeze |
In Case of a Power Outage
If a power outage occurs and you don’t have a backup generator, you can purchase dry ice in many grocery stores and use it to freeze your breast milk in a cooler until your power comes back on. Keep this cooler in a well-ventilated area outside your living space due to the risk of excessive carbon dioxide in an enclosed space.
If your frozen milk thaws partially, it can be refrozen if ice crystals are present. If it thaws completely, it cannot be refrozen and must be used within 24 hours or discarded.
Replacing Parts on Schedule
Check your manufacturer’s manual to see when parts need replacement. Replace damaged parts immediately. Here is a typical schedule.
| Pump Part | Replacement Frequency |
|---|---|
| Membranes or duck bills | Every 2 to 4 weeks |
| Backflow protectors | Every 3 months |
| Tubing | Every 3 months (or sooner if mold grows within) |
| Flange and connectors | Every 6 months |
Helpful Tips
As your baby becomes more interactive, you may feel torn between spending time pumping and interacting with your baby. Possible ways to address this include:
- Pump with a hand-free nursing bra with the pump motor in a backpack with a battery pack, which allows you to do other things like bottle feeding, etc.
- Put your baby in a nearby playpen with toys that only come out during pumping.
- Have older children engage with aspects of baby care while you pump.
To learn more, order the Fed Is Best book available in print, ebook, and audiobook.