Elastic Nipples: The Most Common Flange Sizing Mistake??

If you’ve been blaming your low milk output or pumping discomfort on “elastic nipples,” it might be time for a reality check. In fact, I’d bet there’s a strong chance the problem isn’t elasticity at all—it’s an ill-fitting flange. And that one simple detail could be the difference between constantly falling behind and finally meeting your baby’s needs with confidence.

Last week, I worked with a mom named Jacqueline who thought for sure she had elastic nipples. She was ready to overhaul her entire setup, try new pumps, and buy all the gadgets. But after one adjustment to her flange size, she went from being a full bottle behind to completely meeting her baby’s daily needs. No new pump. No complicated hacks. Just the right flange.

It’s time to bust one of the biggest myths in the pumping world—and it starts with understanding what elastic nipples actually are, and why so many moms are misdiagnosing themselves.

(This post was originally a video. Check it out, here!)

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What Are Elastic Nipples?

Let’s clear this up: all nipples have some degree of elasticity. They’re made of skin and tissue—that’s how the body works. True hyperelastic nipples, though, are a different story. These are nipples that stretch two to three times their normal length during pumping, often pulling all the way down the flange tunnel and hitting the back.

That level of stretchiness? It’s rare.

Most of the time, when a mom thinks her nipple is “stretching too far,” it’s actually not the nipple itself—it’s the wrong flange size pulling in too much surrounding tissue (including areola). It creates the illusion of elasticity when the real issue is a mismatch between your nipple and the flange you’re using.

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Why Misinformation Is So Common

It’s so easy to fall down the internet rabbit hole when you’re trying to figure out what’s “wrong” with your pumping setup. But when it comes to elastic nipples, online advice can often do more harm than good.

I’ve seen countless moms get swept into expensive product recommendations, hacks involving DIY inserts, or switching pumps altogether—when the real issue was simply an incorrect flange size. Forums and social media groups mean well, but without someone trained to assess nipple tissue behavior, these suggestions often miss the mark. Before you buy another flange, pump, or insert, make sure you’ve ruled out the basics with professional support. Most of the time, what looks like elasticity is just a sizing problem in disguise.

Here’s what’s actually happening most of the time:

If you’re using a 24mm or 27mm flange (which are the sizes most pumps come with) but actually need something like a 15mm or 17mm, you’re going to see a lot of tissue getting pulled into the tunnel. That doesn’t automatically mean elasticity—it just means you’re using a size that’s too big.

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Why Flange Size Matters More Than You Think

This isn’t just about comfort. The wrong flange size can mess with everything. Here are four critical reasons flange sizing should never be overlooked:

1. Comfort

Pumping should not hurt. If your nipples feel sore, stretched, or irritated, your flange is likely too big or too small. Even if you think it feels “fine,” you might be surprised how much better it can feel with the correct fit. I hear it all the time: “Wow, I didn’t know it could feel like this.”

2. Milk Output

A poor fit can leave milk behind—which tells your body, “We don’t need that much next time.” Over time, this can reduce your supply. When clients adjust their flange sizes properly, they almost always see a jump in output and feel more emptied after each session.

3. Speed + Letdowns

The right flange helps trigger multiple letdowns faster. If you’re stuck getting only one letdown or pumping longer than 30 minutes per session, flange sizing is the first place I’d look.

4. Tissue Health

Long-term use of the wrong size can cause trauma—cracks, swelling, even bleeding. And unfortunately, damage isn’t always visible to the untrained eye. I often review photos from clients who didn’t feel pain, but the signs of internal swelling were clear.

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Most Moms Are Wearing the Wrong Size

Let me share a story. One mom came to me frustrated with her wearable pump. She thought the issue was the pump itself. But when we took a closer look, she was using flanges that were way too big—she needed a 15mm on one side and a 17mm on the other. After making that switch, she saw a major improvement in both comfort and milk output, especially with her second and third letdowns.

She had also mis-measured herself using a circular flange ruler—something I don’t recommend. It had her at a 21mm base when she was actually 4–6mm smaller. That might not seem like a big deal, but when it comes to pumping, millimeters matter.

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What If You Do Have Elastic Nipples?

Genuine hyperelasticity is rare—but yes, it exists. If that’s truly your situation, here’s what we usually do:

1. Accurate sizing first — no hacks, no gear swaps until the baseline is correct. Try to stay as close to your actual nipple base measurement as possible.
   
2. Use long tunnel soft silicone flanges — products like Lacteck Flanges or Pumpin Pals work well because they grip tissue gently and allow stretch without damaging it.
   
3. If wearables are a must, look for soft silicone cups and inserts, but be realistic—many wearables simply won’t work well with very elastic nipples.

And sometimes? You have to accept that wearables aren’t the best fit. I know that’s not what you want to hear, but for some moms, the tradeoff isn’t worth the supply drop or discomfort.

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Flange Sizing Isn’t One-and-Done

Your flange size can (and likely will) change during your pumping journey. I’ve had clients go from a 24mm all the way down to a 13mm over the course of a month. Why? Because early swelling and incorrect sizing can mask your true nipple size. As the tissue calms and heals, we reassess and resize.

Common times when flange sizing may shift:

• A few weeks postpartum (as birth hormones stabilize)
• At 3, 6, 9, and 12 months (growth spurts, schedule changes, returning to work)

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So… Do You Actually Have Elastic Nipples?

If you’re not 100% confident in your flange size—or you’re still not sure if elasticity is the real issue—it’s time to stop guessing. We covered this in depth (with real visuals) in our recent free webinar on building, protecting, and controlling your milk supply. It’s not all about flange sizing, but I do walk through common mistakes, flange myths, and real examples of elastic vs. non-elastic nipples. You’ll leave with clarity and a much stronger understanding of how to build a pumping setup that works for you.

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Your pump is not a baby. It needs the right inputs to work effectively. And if you’re ready to stop second-guessing every session and start feeling confident in your pumping routine, come join us. There’s a link below to watch the workshop or apply to work with our team.

Happy pumping—and here’s to finally figuring out what actually works for your body.