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Breast Shield Sizing Guide: How to Get the Right Fit

Breast Shield Sizing Guide: How to Get the Right Fit

Using the right size breast shield is essential to pumping success. Follow this guide to measure and get the right fit.

Why size matters

Breast shield, also referred to as a flange, size can directly impact milk supply. If the incorrect size is used, it can lower milk supply, a pumping parent’s nightmare. In addition to supply issues, it can also lead to clogged ducts, nipple pain or injury, and affect the overall comfort during pumping sessions. Using the correct flange size is incredibly important!

How to measure your breast shield size

First, stimulate your nipple, making sure the nipple is erect when measuring. Use Cimilre’s Breast Shield Sizing Guide, a tape measure, or a ruler to measure the diameter of your nipple (the horizontal width across) in millimeters (mm). Be sure to measure only the nipple and exclude the areola, the darker area around the nipple.

Cimilre's printable breast shield flange size ruler

Once you have measured your nipple, add approximately 2 - 4mm. For instance, 18mm + 3mm = 21mm breast shield size.

It’s important to measure both sides since one side may require a different size than the other.

Nipple size may even change throughout your pumping journey. Keep an eye on your pump sessions; if you notice a change in supply or comfort, it may be time to remeasure and get a new size breast shield.

Breast shield good fit, too small, too large

Is this the right fit?

These are indications you are using the correct size breast shield/flange:

  • The flange fits comfortably around the breast and nipple
  • Only the nipple, or the nipple and a small part of the areola, enters the tunnel when pumping
  • The nipple moves freely when pumping
  • Breasts feel emptied after pumping
  • Milk supply remains the same or improves
  • Pumping sessions are comfortable and free of pain

What to look out for

If your breast shield size is incorrect, the following may happen:

  • Reduced milk supply
  • Pain or discomfort while pumping
  • White or discolored nipple after pumping

Get the right fit

If you tried the two breast shield sizes your Cimilre breast pump came with, but realize you need a new size, we will send you a third set of the size you request for free. Simply fill out the Get the Right Fit form to submit your request.

If you need additional breast shields, valves, or collection kits, browse our pump spare parts. Spare parts are interchangeable for all Cimilre breast pumps.

Still looking to get your breast pump? Get your breast pump through insurance with one of our partners.

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