The 555 rule is a guideline for storing breast milk to maintain its freshness and nutrients. It states that breast milk can be stored:
- At room temperature (up to 77°F/25°C) for up to 4 hours
- In the refrigerator for up to 5 days
- In the freezer for up to 6 months
Following this rule helps ensure breast milk stays safe to drink and retains its nutritional value. However, there are some additional tips to keep in mind when pumping, storing, and feeding breast milk.
Why follow the 555 rule?
Breast milk is a miraculous food source for babies, providing the perfect blend of vitamins, fat, and protein. It also contains antibodies that protect infants from illness. However, it can spoil and lose nutrients if not stored properly.
Bacteria multiply rapidly in breast milk when left unrefrigerated or frozen for too long. Some of the immune properties also start to break down. Following the 555 rule prevents milk from spoiling and becoming unsafe for your baby.
The refrigeration times are based on keeping the milk temperature at or below 39°F (4°C). Freezing prevents bacterial growth and preserves nutrients by slowing down the milk’s molecular activity.
4 hours at room temperature
Freshly pumped breast milk is safe at room temperature for up to 4 hours. The milk should be stored in a clean, closed container to avoid contamination.
Leave plenty of headspace in the container, as breast milk expands when frozen. After 4 hours, it is best to refrigerate or freeze the milk if not being used.
The 4 hour timeline starts from the time the first ounce is pumped. All additional pumped milk can be added to the original container within the 4 hour period. Discard any milk that reaches the 4 hour mark.
An exception is milk expressed while traveling. Travel can expose expressed milk to higher temperatures. In this case, the safe storage time may be shorter.
Why only 4 hours at room temperature?
Breast milk can grow bacteria such as Staphylococcus aureus, Escherichia coli, and Klebsiella pneumoniae when left at room temperature. One study found bacterial growth in pumped milk after just 3 hours unrefrigerated.
Another study showed that refrigerating pumped milk within 4 hours restricted bacterial growth. Refrigerating within 1 hour restricted growth even further. Storing at room temperature beyond 4 hours significantly increases the risks.
5 days in the refrigerator
Refrigerating breast milk is an easy way to safely store it for a few days. According to the 555 rule, breast milk can be kept in the refrigerator for 5 days.
Store milk in clean containers or breast milk storage bags. Leave room for expansion and date the milk so you can follow the 5 day guideline.
The refrigerator temperature should be at or below 39°F (4°C). A separate milk storage refrigerator is ideal but not always necessary. Store milk towards the back rather than the door.
If you won’t use the milk within 5 days, freeze it right away. Breast milk can be refrigerated for longer than 5 days if it is extremely fresh and stays chilled.
Does refrigeration affect nutrients in breast milk?
Refrigerating breast milk leads to some changes in its nutritional makeup. However, it still retains most of its nutrients:
| Nutrient | Effect of Refrigeration |
|---|---|
| Fat | No significant change up to 8 days |
| Total Protein | No significant change up to 8 days |
| IgA Antibodies | No significant change up to 96 hours |
| Lysozyme Activity | No significant change up to 8 days |
| Vitamin C | Up to 30% decrease by day 4 |
| Vitamin A & E | Minimal changes up to 96 hours |
As shown above, most components remain stable. Only vitamin C declines rapidly. Overall, breast milk retains its nutritional quality very well for 5 days in the fridge.
6 months in the freezer
Freezing is the best method for long-term storage of breast milk. According to the 555 rule, breast milk stored in the freezer remains good for up to 6 months.
It is best to freeze milk immediately rather than refrigerating first. Portion milk into 2-4 ounce amounts and store in milk storage bags, containers, or ice cube trays.
Leave space at the top for expansion and try to remove as much air as possible before sealing. Milk stored in the back of the freezer stays colder and keeps longer.
Why 6 months?
Frozen breast milk remains safe and nutritious for at least 6 months. However, some changes can occur with long-term freezing:
- Vitamin C and B12 levels decline over time.
- The milk takes on a soapy odor and taste.
- Fat separates and sticks to the sides of containers.
- Proteins start to break down.
Although freezer burn or absorption of odors may affect taste, the milk remains safe to drink after 6 months. Many nutrients are retained at adequate levels.
Research shows DHA levels, calories, and antibodies remain stable at least 3 months in a regular freezer. One study found acceptable macronutrient levels for 12 months frozen storage.
Additional tips for pumping and storing
Following the 555 rule is a great start for maintaining breast milk safety and quality. Here are some additional tips:
Pumping
- Wash hands thoroughly before pumping.
- Use a dedicated milk storage refrigerator or insulated cooler bag.
- Pump milk in a clean, designated area.
- Avoid adding freshly pumped milk to refrigerated or frozen milk.
Storage
- Store milk in clean containers made for breast milk.
- Use oldest frozen milk first to rotate out supply.
- Label containers with date and time pumped.
- Don’t store milk in door of refrigerator or freezer.
Feeding
- Swirl milk gently before feeding to mix separated layers.
- Do not microwave frozen breast milk to defrost or heat.
- Defrost frozen milk overnight in fridge or in warm water.
- Once defrosted, use within 24 hours.
- Discard any unused reheated milk within 1-2 hours.
Frequently asked questions
Can I combine milk from different pumping sessions?
If the milk is chilled, you can mix newly pumped milk with older refrigerated milk. But avoid adding warm freshly pumped milk to already cold milk.
Do alcohol and caffeine affect stored milk?
Yes, alcohol and caffeine can be transmitted to your milk supply. Avoid pumping for at least 2-3 hours after having more than 1-2 drinks. Wait at least 1 hour after having caffeinated drinks before pumping.
How long can breast milk sit out at room temperature?
Breast milk is safe at room temperature for 4 hours max. To be extra safe, refrigerate or freeze milk within 1-2 hours after pumping.
Can thawed breast milk be refrozen?
Previously frozen milk can be refrozen but only once. Thawed milk should not sit in the fridge for longer than 24 hours before re-freezing.
Does pumped milk need to be warmed before feeding?
It is not necessary to warm refrigerated or thawed milk before feeding. However, some babies prefer the warmth. Slow warming in warm water is best.
Conclusion
Following the 555 rule is important for retaining breast milk safety and nutrients. Breast milk can be kept at room temperature for up to 4 hours, refrigerated for up to 5 days, and frozen for up to 6 months.
Take care when collecting, storing, and feeding milk to your baby. Proper handling prevents contamination and spoilage. Stick to the 555 rule as closely as possible, and your breast milk will stay fresh and nutritious.