One of the most important things when pumping breast milk is to make sure that you have the best flange fit, so that pumping isn’t painful and you can maximize your milk supply. Here’s everything you need to know about breast shield sizing.
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What is a breast shield?
Breast shields (also called “flanges” or “horns”) are the part of the pump that actually touches your breasts.
This part fits around your breast, and your nipple is sucked into the tunnel, pulling the milk out.
How are they sized?
Breast shields are sized based on the diameter of your nipple.
This means that it’s possible to have large breasts, but need a small breast shield size. Sizing is based on nipple size, not breast size.
Why is using the correct breast shield size important?
Using the incorrect breast shield size can cause two major problems – pain and decreased milk output.
(You don’t want either of these, which is why it’s a really good idea to make sure you have the right size!)
- If your breast shield is too small, your nipple won’t be able to move freely in the flange “tunnel,†which can cause nipple pain because the fit is too tight.
- If your breast shield is too large, too much of the tissue around your nipple gets pulled into the tunnel. The agitation related to areola getting pulled in where it shouldn’t can bruise that tissue and cause pain and inflammation.
How does this pain, as described above, result in decreased milk output?
First, pain inhibits letdown, so if pumping hurts, it will be harder for you to get your milk to letdown. Additionally, if there is pressure from your flanges where it shouldn’t be, this can cause the ducts to flatten or constrict the flow of milk.
What are some signs that your flanges don’t fit correctly?
Here are a few reasons to consider using a different breast shield size:
- You’re having pain when you pump.
- Your nipple can’t move freely in the tunnel and turns red.
- More than a little areola is pulled into the breast shield.
- Your breasts don’t feel empty after 15-20 minutes of pumping.
- Your nipples stretch far into the flange, almost to the end of the connector.
What sizes are available?
Different breast pump manufacturers sell different breast shield size options. A few examples:
- Spectra: 20mm, 24mm, 28mm, and 32mm
- Medela: 21mm, 24mm, 27mm, 30mm
- Motif: 21mm, 24mm, 28mm, and 32mm
Additionally, there are several companies such as Nenesupply and Maymom that make aftermarket breast pump replacement parts, and these may include additional sizes. For example, Nenesupply sells the same sizes as listed above for Spectra, but they also sell 19mm breast shields.
As another example, Maymom makes sizes as small as 19mm and as large as 33mm for Medela breast pumps.
How do you find the correct breast shield size?
So what should you do if you think you might have the wrong breast shield size? You have a few options to try to find the best size for you.
1. Measure with a ruler
You can download a printable breast shield size ruler and use that to measure your nipple size.
Below is an example of what these rulers look like. You cut out each of the circles, and then see which circle best fits your nipple after you finish pumping.
Image copyright Aeroflow Breastpumps. Used with permission.
Legendairy Milk sells a ruler for flange sizing that you can use to measure your breast shield size – use EPUMP for 15% off.
2. Measure with a coin
If you don’t have a printer and want to try measuring your nipple size, you can use coins to do it instead.
Here are the diameters of several U.S. coins that you can use to measure your nipple size (source):
- Dime – 18mm
- Penny – 20mm
- Nickel – 22mm
- Quarter – 24mm
- Dollar – 26mm
- Half-Dollar – 30mm
3. Try several different sizes
Another option, if you don’t want to measure/are finding it confusing or if you are still having pain with the size that you measured for, is buying and trying several different sizes.
One way to do this is to buy one size up and one size down from what you measured for or what you’re using now, and see what feels best.
The upside to this method is that you can be sure the size you’re using is best for you compared to other options. The downside is obviously that you might end up buying a lot of sets of breast shields that don’t fit, and that adds up.
Is it possible to need different size breast shields?
Yes. It’s possible to have nipples that are two different sizes; some amount of asymmetry between breasts is normal. (Just like it’s possible – even common – have lopsided breast milk output from your breasts.)
It’s a good idea to measure both sides to ensure each side has the correct size.
If you need different sizes, just buy one of each size, and you have two sets of breast shields that will fit you perfectly.
Can your breast shield size change over time?
Yes. Therefore, if you start feeling discomfort when pumping, it’s good idea to measure yourself or try a different size even if you were sized before.
What if you can’t find a size that fits you?
If you are in between sizes, BeauGen cushions are a good option, as they will reduce your flange size by about 2mm. So for example, if you measure yourself at 26mm and have a Spectra breast pump, you could try using 28mm flanges with cushions.
Beaugen cushions are available on amazon, but you can get a 10% discount buying directly from Beaugen with the promo code EPUMP.
However, some women struggle to find ANY size that feels comfortable for them.
One cause for this can be elastic nipples. With elastic nipples, the nipple stretches to fit whatever size breast shield is being used – sometimes reaching to the end of the tunnel.
Usually, with elastic nipples, you will want to try breast shields that are a different shape and material (silicone), such as Pumpin Pals or LacTeck BabyMotion flanges. These (along with BeauGen cushions) can sometimes help keep your nipples from stretching out.
You can use the code EPUMP214 for 10% off LacTeck BabyMotion flanges.
More on alternate breast shields options here.
Have you struggled with breast shield sizing? Feel free to ask any questions about flange fit in the comments!
