Breastmilk Storage Basics

Breastmilk storage can be a confusing topic. Baby Basics Atlanta guest posts to break down breastmilk storage into 3 easy categories and a few quick tips!

In honor of World Breastfeeding Awareness Month Baby Basics Atlanta joins Moms on Call to simplify breastmilk storage into 3 simple categories, a few quick tips and some FAQ’s! Keep reading as Megan Tucker, RN, BSN, Certified Moms on Call Consultant, Lactation Consultant, Childbirth Instructor and Founder of Baby Basics Atlanta walks us through breastmilk storage safety!

General Guidelines

Tip #1: The Rule of 4s (per new CDC guidelines): 

  1. 4 hours: from body and placed out at room temperature.
    • If feeding soon after pumping, this is the best course of action (see tip 3). 
  2. 4 days: in the refrigerator 
  3. 4-6 months: frozen in fridge/freezer combination (one that you are in/out of regularly) 
  4. 6-12 months: deep freeze
  5. 24 hours: in an insulated cooler with ice packs

Tip #2: Use ASAP:

The nutritional quality of breastmilk diminishes, like any other food, once removed from the area where it was made. The best idea is to always use breastmilk as soon as possible (or freeze until ready to use). Can it “go bad”? Yes, but you’ll know it by smell, taste and appearance. Most will never see milk truly spoil. 

Tip #3: Breastmilk is sensitive to temperature change:

Breastmilk is delicate. Extreme temperature changes simply destroy important nutrients in the milk. You worked hard for it so let’s serve our kids the freshest, most nutritionally dense that we have to offer. Repeatedly, warming and cooling is NEVER a good idea. 

Tip #4: Use within 2-3 hours:

Once baby has sipped on it, use breastmilk within 2-3 hours. 


Tip #1: Body–>Fridge–>Freezer:

Body to fridge first. Cool it down slowly. Then fridge to freezer. Avoid body to freezer!

Tip #2: Use your oldest milk first:

Baby Basics suggests placing bottles of pumped milk on a designated shelf in your refrigerator (avoid the door where temperature fluctuates). A good system to have in place is to place bottles in a line; always pull the oldest milk forward and place newly pumped milk in the back of the line. 

Tip #3: Labeling:

Write the date (and time if you’d like) on all bottles with masking tape + sharpie or white board marker on the caps. 

Tip #4: To warm or not to warm? That is the question:

Warming helps dissolve the fats which solidify on the side while in the fridge; you want to reincorporate those wonderful fats for your baby. Warm milk by placing it in a bowl or mug of warm-hot water for a few minutes. Swirl gently before feeding. AVOID shaking vigorously. 

Freezing and Thawing:

Tip 1: Freeze within 24 hours:

If possible, freeze any surplus milk within 24 hours to preserve nutritional quality. 

Tip #2: Breastmilk bricks:

To save space, place bags of breastmilk flat for freezing. 

Tip #3: Seal well!

We like the double zipper storage bags for that extra layer of security. Freeze in 4-6 oz quantities. 

Tip #4: 3 ways to thaw breastmilk: 

  1. Best option for preserving nutritional quality: Place in the refrigerator overnight. Use within 24 hours after fully thawed (full thawed=last ice crystal). 
  2. Have a little time but know you will be needing it soon? Slow thaw in a bowl of cool water. May store any unused milk in the fridge if NOT warmed (use within 24 hours). 
  3. Hungry baby and need it fast? Thaw in a bowl of warm water. Use within 2-3 hours. 

*Avoid refreezing thawed milk. Baby isn’t going to drink it? A breastmilk bath is wonderful for your baby’s skin or if baby is eating baby food, mix with baby cereal. 

*Avoid thawing or heating breastmilk on the stove or in the microwave. 


  1. Can breastmilk and formula be combined in the same bottle? Yes! Mix formula per package directions and combine with breastmilk in one bottle. Once baby has sipped on the bottle, it should be used within 2-3 hours. 
  2. Can I alternate breastmilk and formula bottles? Yes, BUT we like consistency for baby’s GI system. The best advice would be to assess breastmilk totals for the day and pour a consistent amount of breastmilk in all bottles and top off each with the formula needed to reach your baby’s average bottle size. 
  3. How do I reduce washing of bottles and pump parts? Pump into the bottles you intend to feed from. Baby Basics can help you with pump and bottle selections that will help simplify your life.
  4. Do I need to sterilize pump parts and bottles after every use? NO! Hot, soapy water and a good bottle brush or top rack of the dishwasher is sufficient for cleaning.
    • *Note: If baby has a compromised immune system, thrush or other illness that is highly contagious or hard to get rid of, sterilizing may be necessary. Check with an LC or your provider for more information. 

Need more help breastfeeding, pumping or a combination of both? Reach out! Baby Basics can help. Owner, Megan Tucker, is an RN of 21 years, Moms On Call Consultant, Certified Lactation Consultant and Certified Prenatal Educator with over 14 years of experience helping families achieve their individual feeding goals.

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