A question I’ve been getting more and more is whether is it okay to combine breast milk from different days. Here’s some background on where that question is coming from, and what different sources tell us.
I read this article, and it says that you can’t combine breast milk from different days? Is this true? Why would this be?
I’m not really sure. The linked VeryWell article says:
It is not safe to add breast milk that you pumped today to a container of breast milk that you pumped yesterday or last week.
Personally, I’ve combined milk from different days many times. I assumed this was safe based on what I’d read on Kellymom when my first baby was brand new:
Milk from different pumping sessions/days may be combined in one container – use the date of the first milk expressed.
It’s a little unclear what the VeryWell article means, exactly. It says it is okay to mix milk you pumped on the same day, but not different days.
I’m assuming that the author means milk pumped more than 24 hours apart? Or is she saying that if you pump at 10pm on a Saturday and 1am on a Sunday, as is typical for an exclusive pumper, that that’s not safe to mix? (The implication being that breast milk is affected like Gremlins by the hour of midnight, or something?)
The VeryWell article doesn’t explain WHY this wouldn’t be safe, so I checked the two cited sources to try to find the explanation.
One was the CDC, which says nothing about mixing milk from other days. (On the contrary – it actually talks about how to mix milk from different days.)
The other is a scientific article from 2013 that is behind a medical journal paywall; a reader with access was kind enough to send me a copy. It also does not say anything about mixing milk from different days.
So now I have no idea how to answer this question, except to say that, while I am not a medical professional, I’m not sure why mixing milk from different days would be a problem as long as:
- All of the milk that is mixed is within breastmilk storage guidelines, and
- You treat all of the mixed milk as if it was pumped at the time of the first expressed milk, and
- The milk you’re mixing is the same temperature (adding warm milk to cold milk can allow bacteria to grow more quickly)
Maybe VeryWell’s recommendation comes from a concern that moms just won’t, in practice, treat all of the mixed milk as if it was pumped at the time of the first expressed milk? I’m struggling to come up with another explanation.
For now, in the absence of additional information, I would suggest using Kellymom’s guidance for combining breast milk from different days. However, let us know your thoughts in the comments.