Pumping Breast Milk but Barely Getting Anything? Your Flange Size Might Be the Problem!
What if I told you that the breast pump flange that came in your box might be making pumping harder than it needs to be?
Yep. That little plastic funnel that attaches to your breast could be the reason you're sitting there pumping for 30 minutes, getting sore nipples, and wondering why on earth you're barely collecting any milk.
And here's the kicker: You could have a perfectly healthy milk supply and STILL struggle to get milk out with your pump!
Ladies, we need to talk.
On this episode of The Boob Business Podcast, I sat down with fellow International Board Certified Lactation Consultant (IBCLC) Jeannette Messite Fromm, a nationally recognized educator in breast pumping and flange fitting, to discuss something that honestly deserves WAY more attention in the breastfeeding world.
We're talking about breast pump flange sizes, the outdated advice that many moms are still receiving, and some fascinating research that could change how we approach pumping altogether.
If you're pregnant, exclusively pumping, preparing to return to work, or wondering why pumping feels like a medieval torture device, this episode is for YOU.
First, What the Heck Is a Breast Pump Flange?
If you're new to pumping, let's start with the basics.
A breast pump flange (sometimes called a breast shield) is the funnel-shaped piece that fits over your nipple and connects to your breast pump.
Its job is to help create the vacuum that removes milk from your breasts.
Sounds simple enough, right?
Well, here's where things get interesting.
Most breast pumps traditionally come with flanges measuring approximately 24 mm or 28 mm. For years, moms have been told to use the sizes included with their pumps or measure their nipples and add a few extra millimeters.
But according to Jeannette, those traditional sizing recommendations aren't supported by the evidence many people assume they are.
In fact, she argues that most women need much smaller flanges than the ones included with their pumps.
Think about that for a second.
We've spent years encouraging mothers to pump more frequently, increase suction, try supplements, and troubleshoot their milk supply when sometimes the problem might be something as simple as the wrong piece of plastic!
Could the Wrong Flange Size Be Affecting Your Milk Output?
Let's say you're pumping three or four times a day.
You're doing everything you think you're supposed to do. You're drinking your water, eating your nutritious meals, and following all those pumping tips you found on Instagram.
But you're still struggling.
Before you assume you have a low milk supply, let's consider another possibility.
What if your pump isn't removing your milk effectively?
An improperly fitted flange can contribute to:
Painful pumping sessions
Nipple swelling and irritation
Inefficient milk removal
Longer pumping sessions
Frustration and unnecessary worry about milk supply
And this is particularly concerning because many moms use the amount of milk collected during pumping as a way to judge how much milk they're producing.
But here's something I really want you to understand.
The amount of milk you pump does NOT necessarily reflect how much milk your body is capable of making.
Milk output can be influenced by your pump, flange fit, pumping technique, timing, and how your body responds to pumping.
So before you diagnose yourself with a low milk supply based on what you see in your collection bottles, please consider getting some professional guidance.
The Research That Has Lactation Professionals Talking
Now, this is where our conversation gets especially interesting.
Jeannette shared details about a research study she conducted with Dr. Lisa Anders examining traditional breast pump flange sizing recommendations compared with individualized flange fitting (Anders 2025).
The study included approximately 36 breastfeeding mothers whose babies were between one and six months old.
Participants compared pumping sessions using traditionally recommended flange sizes with sessions using flanges selected through individualized fitting.
And the preliminary findings Jeannette shared were pretty fascinating.
Participants collected approximately half an ounce more milk per pumping session, on average, with their individually fitted flanges.
Some also reported greater comfort and shorter pumping sessions.
Now, half an ounce might not sound like much.
But if you're pumping several times a day, those additional ounces can add up!
And if you've ever been that mom staring at the bottom of a pumping bottle, hoping for just ONE more ounce, you know exactly why this matters.
At the time of our interview, the study was awaiting publication, so these findings should be considered preliminary until the full research is available for review.
Still, they raise an important question: Have we been approaching breast pump flange sizing the wrong way?
Watch our interview to hear Jeannette explain her research.
How Do You Know If Your Breast Pump Flange Is the Right Size?
Here's where Jeannette challenges some of the advice you've probably heard.
Traditional recommendations often instruct moms to measure the base of their nipple and add a certain number of millimeters to determine their flange size.
Jeannette's approach is different.
Her Flange FITS Guide starts with measuring the nipple tip and then trying different flange sizes to evaluate comfort and milk removal.
And here's the important part: There isn't one magic mathematical formula that determines the perfect flange size for every woman.
Your nipple measurement is a starting point, not the final answer.
Jeannette encourages moms and lactation professionals to consider three important things:
Comfort: Does pumping feel comfortable, with little more than a gentle tug?
Milk flow: Are you seeing good milk flow during pumping?
Efficiency: Are you able to remove milk effectively without unnecessarily long pumping sessions?
She also explains why a nipple gently gliding along the inside of the flange tunnel isn't necessarily a sign that your flange is too small.
I know. That may be completely different from what you've been told!
This is exactly why I recommend watching our video interview rather than just listening to the audio. We demonstrate flange sizes and discuss what to look for during a fitting.
Pregnant? Here's Why You Should Learn About Pumping BEFORE Your Baby Arrives
One of my biggest passions as a lactation consultant is helping women prepare for breastfeeding before their babies are born.
Because after working with thousands of mothers and babies, I can tell you that those first few weeks are incredibly important.
And the last thing I want is for you to be sitting in a hospital bed, exhausted from childbirth, trying to figure out how to use a breast pump that doesn't fit you properly.
Here's something many pregnant women don't realize.
You might need to pump much sooner than you expect.
Maybe your baby has difficulty latching.
Maybe your baby needs additional milk.
Maybe your baby is admitted to the NICU.
Or maybe you simply decide that pumping will be part of your infant-feeding journey.
Whatever your circumstances, knowing a little about your breast pump before delivery can save you a tremendous amount of frustration.
That doesn't mean every mom needs to start pumping immediately after birth. If breastfeeding is going well and your baby is transferring milk effectively, additional pumping may not be necessary.
It means understanding your options and knowing when to ask for help.
And while you can begin learning about flange sizing during pregnancy, using a breast pump before delivery should be discussed with your maternity care provider, particularly if you have risk factors for preterm labor.
This Is Exactly Why I Wrote Milk'D
When I wrote Milk'D: Finding Your Flow in the First Few Weeks of Breastfeeding, I wanted to create the resource I wish someone had handed me when I was a new mom.
Not another book that makes breastfeeding sound like some magical experience where everything falls perfectly into place.
Because sometimes it doesn't!
I wanted something practical, honest, encouraging, and filled with the information that can help moms prepare for the REALITY of feeding a newborn.
My goal is to help you understand what to expect, recognize when something isn't going well, and feel confident asking for help before small challenges become bigger problems.
Whether you're planning to exclusively breastfeed, pump, bottle-feed expressed milk, or combine feeding methods, preparation matters.
Get your copy of Milk’D here: Amazon, Barnes & Noble, Apple Books
What About Wearable Breast Pumps? Are They Just as Good?
Ahhh, wearable pumps.
They're convenient, discreet, and let's face it, the idea of pumping while doing laundry or chasing a toddler sounds pretty fabulous.
But convenience doesn't always equal effectiveness.
During our interview, Jeannette explains some of the challenges associated with wearable pumps, including shorter flange tunnels, silicone inserts, and differences in how the pump fits against the breast.
Some moms respond beautifully to wearable pumps.
Others struggle to remove milk effectively, even when they're producing plenty of milk.
And this is where comparison can get us into trouble.
Just because your best friend can pump five ounces using a particular wearable pump doesn't mean that same pump will work equally well for you.
Your breasts are different. Your anatomy is different. And your response to a pump may be different.
A pump that works beautifully for one mom might be completely wrong for another.
If your wearable pump isn't working well, don't immediately assume your milk supply is the problem.
Sometimes changing the flange, adjusting the fit, or trying a different pump can make a meaningful difference.
Pumping Shouldn't Be Something You Have to Endure
Can we please retire the idea that pumping is just supposed to hurt?
Because I hear this from moms far too often.
They assume sore nipples, uncomfortable suction, and swelling are simply part of the experience.
They're not things you should automatically accept as normal.
Jeannette and I discussed how some moms continue using painful pump settings because that's what someone told them to do or because they saw a pumping routine on social media.
Ladies, Instagram is not your lactation consultant!
More suction doesn't automatically mean more milk.
And pumping longer doesn't necessarily mean you're pumping better.
If pumping hurts, something deserves a closer look.
That might mean evaluating your flange fit, suction settings, pumping frequency, or other factors affecting your comfort.
The important thing is not to ignore the problem.
The Bottom Line: Your Boobs Deserve Better!
If there's one thing I hope you take away from this conversation, it's that successful pumping isn't simply about working harder.
Sometimes it's about having the right equipment, the right information, and the right support.
And please, don't spend your entire breastfeeding journey comparing your pumping output to what someone else is posting online.
Your body is not their body.
Your baby is not their baby.
And your breastfeeding journey doesn't have to look like anyone else's.
If you're pregnant, this is your opportunity to prepare before your baby arrives.
If you're already pumping and struggling, I hope this conversation encourages you to ask more questions and explore whether your equipment is working for you.
Because you deserve better than painful pumping sessions and unnecessary stress.
Ready to Learn More?
Watch the full episode of The Boob Business Podcast.
Jeannette and I dive deeper into flange sizing, pumping myths, wearable pumps, and the research challenging some long-standing recommendations in the lactation world.
You'll also hear our candid discussion about what we wish more hospitals, breast pump manufacturers, and lactation professionals understood about pumping.
Listen to the full podcast episode here:
Pregnant or preparing to breastfeed? Grab a copy of Milk'D!
My book, Milk'D: Finding Your Flow in the First Few Weeks of Breastfeeding, was written to help you navigate the early weeks with practical information, realistic expectations, and a whole lot more confidence.
Because breastfeeding might be natural, but that doesn't mean it always comes naturally.
And you shouldn't have to figure it all out alone.
Purchase Milk’D here: Amazon, Barnes & Noble, Apple Books
With love and a little boob wisdom,
Naiomi Catron, RN, IBCLC
Founder, Milk Diva Lactation
Host, The Boob Business Podcast
Author, Milk'D: Finding Your Flow in the First Few Weeks of Breastfeeding
References:
Anders, L. A., Mesite Frem, J., & McCoy, T. P. (2025). Flange size matters: A comparative pilot study of the Flange FITS TM guide versus traditional sizing methods. Journal of Human Lactation, 41(1), 54–64.
