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7 Common Myths about Pumping Breast Milk Debunked

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There is a lot of confusion and misinformation surrounding pumping, pumped milk, hygiene, and the safe storage of milk. It’s important to address the common myths to avoid unnecessary stress for families. As a pediatrician and IBCLC, I’ll debunk 7 common myths about pumped breast milk.

Myth: Pumped breast milk is not the same as receiving breast milk from the breast

I’m not sure who started this myth, but it’s problematic as pumping can save many women’s breastfeeding journey. Pumping is equivalent to feeding at the breast, and when breastmilk is stored correctly, it contains the same nutrient profile as a baby receiving it directly from the breast.

Myth: You need to sterilize pump parts every day

Sterilization is only needed if parts are new. Otherwise, wash with warm water and soap or utilize the fridge hack and wash at the end of the day. Save your time – there is no need to sterilize multiple times a day.

Myth: Breast milk of different temperatures cannot be pooled into the same container

This is also debatable. The CDC recommends bringing freshly pumped milk to the same temperature as milk in the fridge before combining so the fresh milk doesn’t “rewarm” the old milk. However, there is no clinical or research evidence to show pooling different temperatures is a concern for breast milk properties or an increased risk for infection.

I’m not concerned that freshly pumped milk is too warm to destroy the properties of refrigerated milk.

This is a personal decision based on your comfort level – but we pool freshly pumped milk with refrigerated milk at home.

Myth: The freezer hack for storing pump parts is not OK

The CDC mentions that pump parts should be cleaned after every use with warm water and soap. Many women put pump parts directly in the fridge in a closed container or Ziploc bag to use at the next pumping session (no washing, cleaning, etc.). Placing pump parts into the fridge slows bacterial growth, and the milk residue on the parts doesn’t spoil. For many women, this can save their pumping journey due to the time saved from not having to clean multiple parts multiple times daily. If you try the freezer hack, remember to wash the parts at the end of the day.

This is also your choice, as some women will not feel comfortable doing this. If your baby is premature or your baby has health concerns, clear this option with your baby’s clinician. I personally have two sets of all my pump parts and wash with soap and water each time since having the two sets works for me.

Myth: Breast milk should not be shaken

Shake it. Stir it. Do a backflip with it in your arms. Whatever you need to do to mix the contents before pouring it into a bottle. Some believe shaking breast milk breaks down the proteins in the milk and diminishes the nutritional value. This is not proven and clinically we see no concern related to shaking breast milk with our normal human strength prior to drinking. Shaking breast milk and formula can increase bubbles, which can cause some increased gas in some babies. If this happens, you can consider stirring the breast milk.

We shake the milk up in our house.

Myth: You should feed morning milk pumped during the morning and evening pumped milk during the evening

This is related to the timing and production of hormones like cortisol and melatonin. These hormones are naturally created by babies as they grow so there is no need to stress about this detail if you are pumping. I recommend pooling milk for the day so they get a mixture of nutrients. Think – formula-feeding families are not panicking about this so pumping families shouldn’t either. Your 4-week-old being up at night is not because your milk is loaded with cortisol, rather it’s most likely because their natural sleep-wake cycle has not been established.

We pool breastmilk in our home without specifying the morning or evening milk.

Myth: If your baby doesn’t finish a bottle, you have to throw the remaining milk away

CDC guidelines say to throw away milk two hours after use due to concern of bacterial contamination from saliva/backwash; however, you can consider using it at the next feeding as long as it’s within four hours and smells okay.

Place in fridge or in a cooler bag with ice.

Do not refreeze the milk and make sure to change the nipple out so there isn’t saliva from the prior feeding. If the milk was heated, it should be used at the feeding and any extra should be discarded or saved for a milk bath.

We use the “next feeding rule” in our house.

Key Takeaways

  • Clear any concerns about hygiene or storage with your child’s clinician, especially if your baby is premature or has any medical condition
  • Consider what you feel comfortable with, which may be different from what someone else is doing
  • Don’t shame other moms who may do things differently

Check out the PedsDocTalk “Pumping” highlight on Instagram for more!

P.S. Stay up to date on the latest news on all things child health and parenting with the PedsDocTalk newsletter!

Dr. Mona Admin

Hi there!

I’m a Board Certified Pediatrician, IBCLC, and a mom of two.

I know the ups and downs of becoming a mom and raising kids.

I help moms ditch the worry and second-guessing so you can find more joy in motherhood.


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All information presented on this blog, my Instagram, and my podcast is for educational purposes and should not be taken as personal medical advice. These platforms are to educate and should not replace the medical judgment of a licensed healthcare provider who is evaluating a patient.

It is the responsibility of the guardian to seek appropriate medical attention when they are concerned about their child.

All opinions are my own and do not reflect the opinions of my employer or hospitals I may be affiliated with.