Why “only 5% of women can’t make enough milk” is a myth

low milk supply statistics, low milk supply myths

This post is a sidebar of an earlier blog series about Low Milk Supply. You can read my low milk supply series here.

Anywhere people are talking about breastfeeding, you’re going to hear someone confidently announce that only 5% of women can’t make a full milk supply. It pops up all the time- in Facebook groups, on Instagram & TikTok, in textbooks, in news articles

This statistic is repeated so often that people don’t even think to question it- they just repeat it, and use it as fodder to support whatever particular lactation issue they’re talking about. 

Usually I see it being used to gaslight mothers and fathers into thinking that their low supply is either 1) their fault or 2) completely made up because if only 5% of people can’t make enough milk, either you did something wrong or YOU are wrong and you actually make plenty of milk.

When I wrote my Masters thesis on low milk supply and perceived low milk supply in 2014, I wasn’t yet an IBCLC and a lot of what I knew came from textbooks.  I came across this little factoid pretty often and as I was taught in my research methods course, I would try to figure out exactly WHERE this number came from, but each citation led to another citation that pointed back to the first one.

This 5% thing has ALWAYS bugged me. I called it “the mythical 5%”. Every time it rears its ugly head I think about how frustrating it was to try to track down the source of the info.

So a couple of weeks ago, I saw the 5% being quoted yet again on Instagram. And I decided to go back at look at my research and see if I could get any closer to the source now that a few years had passed.

And you know what? I found it. And it’s just as I thought.

Come down a little rabbit hole with me, will you?

First of all, before we even get into where this statistic came from, I’ve got a bone to pick.

See, the statistic does not say that only 5% of women can’t make enough breastmilk.

When you trace it back to the most cited source, the WHO Bulletin supplement edited by James Akre in 1989, you find the actual quote is:

"it appears that a maximum in the range of 1-5% of women experience lactation failure on purely physiological grounds"

Akre, J. (1989). Health factors which may interfere with breast-feeding. WHO Bulletin Supplement, 67, 41-54

What does “purely physiological grounds” mean? It means that something about someone’s physical body itself is causing the problem, and the normal function of a gland or organ is impaired.

So first of all, this automatically wipes out any issues related to the baby. Lots and lots of things about the baby/babies in a family can cause low milk supply- weak suck, tongue tie, low muscle tone, poor latch, sleepy feeds, and on and on and on. We take all of these off the table when we talk about “purely physiological grounds”. 

What about what we call lactation management issues? You know, not telling the body to make milk frequently enough, not removing any milk for the first days after birth, birth interventions or complications, poor flange fit, crappy pump, yada yada yada? Not “purely physiological grounds.”

Nope, we’re only talking about the breast’s physical ability to create milk.

Don’t even get me started on the “maximum in the range of 1-5% of women” part of this… can a maximum be a range? I’m terrible in math but that seems like a really squishy statistic there.

Anyway… where did Akre get this from? What study is he citing? What research? Surely this vital information is evidence based! 

Akre cites Neville & Neifert’s 1983 textbook LACTATION: Physiology, Nutrition, and Breast-Feeding. 

And this is where I hit a research wall for years. I couldn’t find a copy of this text ANYWHERE. Digital, scanned, hardcover, anything. 

Up until 2 weeks ago, when a copy popped up on a used textbook site for $15. I have never hit the BUY button so fast!

lactation textbook by Neville & Neifert

My copy arrived, signed by the author with a bunch of super interesting notes & scribbles & business cards from the 80s stuffed into it. I immediately sat down to find the mythical 5% and the research behind it.

And it’s here… but not how I expected.

"A false notion, current among breast-feeding enthusiasts, is 'every woman can nurse.' While this philosophy is useful in combating the professional tendency to wean at the slightest obstacle, it appears likely that 1 to 5% of women experience lactation failure on a physiologic basis."

Neville, Margaret, and Marianne Neifert. Lactation Physiology, Nutrition, and Breast-Feeding. Plenum Press, 1983. ‌

Neville & Neifert aren’t talking about low milk supply. They’re talking about someone’s breast/breasts failing to make milk. That’s not low supply… that’s no supply.

And what’s the cited study, you ask? Where did they get this number? What’s in the footnotes, what research is referenced?

Nothing. There’s nothing.

The book just says it.

I’m certainly not calling the authors liars- I’m sure they got this statistic from somewhere- but I have reached the bottom of the rabbit hole and it’s… just a dirt floor.

So WHY are people constantly parroting this statistic all over the place- and even worse, stating it incorrectly?

Is this statistic supposed to be reassuring for anyone who is dealing with low milk supply? If so, and it’s helpful, fabulous! 

But if the statistic is being used to tell people they’ve got no excuse and they’re just not trying hard enough, well, they’re totally misquoting the statistic. And they need to know that they’re wrong or this is never going to stop circulating.

So, if you run into the mythical 5% from here on out, send them my way. You have my explicit permission to share this blog post and help educate people so we can stop spreading this misinformation.

There’s a lot of false news on the internet I can’t do anything about… but busting the 5% low milk supply myth? THAT I can do.

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