The newest breast milk storage guidelines from the AAP
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The new recommendations were first noticed on Reddit.
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Suggested SEO Title: AAP Breast Milk Storage Guidelines: What Changed and What’s Current
Suggested Meta Description: The AAP updated breast milk storage guidelines in 2021 to allow mixing warm and cold milk. Here’s what changed, what didn’t, and what the latest research says.
Suggested H1: AAP breast milk storage guidelines: Here’s what actually changed (and what hasn’t)
AAP breast milk storage guidelines: Here’s what actually changed (and what hasn’t)
Whether you’re deep into your pumping journey or just getting started, breast milk storage guidelines are one of those things you want to get right—but the rules can feel like a moving target. For a full breakdown of breast milk storage basics, temperatures, timelines, and tips, head to our complete guide: How to store and thaw breast milk. Below, we’re zeroing in on the AAP’s guidelines specifically—what’s changed over the years and what pumping parents need to know right now.
What the AAP changed in 2021
In 2021, the American Academy of Pediatrics (AAP) quietly updated the FAQs section of their breastfeeding guidance—and pumping parents everywhere had reason to celebrate. A savvy Redditor was among the first to notice the changes, and the news spread fast.
The big update: The AAP’s revised FAQs stated that parents can mix warm and cold pumped breast milk together, and even recommended pooling milk pumped within 24 hours to help even out the variability in nutrients that can occur depending on pumping time or how fully the breast was emptied.
Previously, the AAP recommended that pumped milk of different temperatures should not be combined—that warm milk needed to be cooled in a separate container before being added to already-cold milk. If you’ve ever pumped breast milk, you know the mental calculus involved in tracking temperature, timing, quantity, and expiration dates—so eliminating that extra step was a real win.
What the AAP’s updated guidelines say about breast milk storage
According to the AAP’s updated FAQs, the guidance for breast milk storage emphasizes cleanliness over perfection. The key points include:
Hand washing and clean (or new) containers are recommended. Plastic or glass containers are both fine—there’s no evidence that one is better than the other.
Minimizing milk transfers is encouraged, since fat and calories can get left behind on container walls. Pumping directly into storage containers when possible is ideal.
Mixing warm milk and cold milk is OK. Parents can also consider pooling milk from a full 24-hour period together, which may help balance out the natural variability in fat content and nutrients from session to session.
The emphasis on pooling was a big deal. Depending on the length of a pumping session or the time of day, the nutrient mix—particularly fat and sugars—in expressed breast milk can vary quite a bit. Combining milk from multiple sessions helps ensure that every bottle your baby gets is nutritionally balanced.
Worth noting: In September 2021, the AAP removed some of this updated FAQ language from their website, including the specific guidance on mixing warm and cold milk and pooling. The underlying AAP policy statement on breastfeeding (most recently updated in 2022) and the AAP’s milk storage guidelines page remain the most current official resources. Motherly continues to monitor the AAP’s guidance and will update this article if any new changes are announced.
The pitcher method: Why pumping parents love it
Even before the AAP updated its FAQs, many pumping parents were already using the pitcher method, which involves combining expressed breast milk from multiple sessions (within 24 hours) into one large pitcher or container in the fridge.
The benefits are real: fewer bottles cluttering up the fridge, a simpler process for transferring milk to feeding bottles, and—critically—less milk wasted. When you pour milk from container to container, some of the fatty compounds stick to the walls, reducing the fat content of what your baby actually drinks. With a pitcher, you can use a rubber spatula to easily scrape the good fats off the sides and gently swirl them back into the milk before pouring into a bottle. That’s much easier to do in a large pitcher than a small baby bottle.
What about the recent buzz around breast milk storage rules?
If you’ve been on Instagram or parenting forums lately, you may have seen conversations questioning whether official breast milk storage guidelines—particularly the CDC’s—are more conservative than they need to be. Researchers and parenting voices, including economist and Expecting Better author Emily Oster, have pointed to studies suggesting that breast milk may stay safe at room temperature and in the fridge longer than current guidelines indicate, and that reusing a partially finished bottle may carry less risk than the rules imply.
So has anything officially changed? Not yet. The AAP has not issued new guidelines in response to this conversation, and the CDC’s storage recommendations remain the same. The research being cited is real—but much of it is small-scale, older, or not yet peer-reviewed. None of it has been adopted into official AAP or CDC policy.
That said, the growing body of research is worth watching. If future studies confirm that current timelines are overly cautious for healthy, full-term babies, it’s possible that official guidelines could be updated down the road. For now, the safest approach is to follow the CDC’s current storage recommendations and talk to your pediatrician if you have questions about what works for your family.
Important caveat: Even experts who advocate for more relaxed timelines note that premature babies, NICU babies, and babies receiving donor milk may need stricter handling. When in doubt, talk to your pediatrician.
The bottom line for pumping parents
The AAP’s most significant recent change to breast milk storage guidance came in 2021, when their FAQs briefly reflected a more relaxed approach to mixing milk temperatures and pooling. While some of that specific FAQ language was later removed, the broader AAP guidance—including its 2022 policy statement—continues to support practical, evidence-based approaches to breast milk handling for healthy, full-term babies.
The conversation around whether storage rules should be loosened further is very much alive, and we’ll continue to update this article as new research or official guidance emerges. In the meantime, for everything you need to know about storing, thawing, and handling breast milk, check out our complete breast milk storage guide.
A version of this article was originally published on September 2, 2021. It has been updated.
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