How do I know what size breast pump flange I need?


One of the most common (and most commonly missed) reasons why mother experience expressing difficulties is an ill-fitting breast pump flange. With breast pump flanges one size most certainly doesn’t fit all.

The flange is the part of the breast pump that fits onto your breast with the tunnel into which your nipple gets pulled. Flanges are available with different diameter tunnels.

When choosing a breast pump it’s important to check if the manufacturing company has different flange sizes available. Most ‘bottle-brand’ pumps that you buy off the shelf do not.

In fact, these often not even state their flange sizes on the box, so you may want to test one from a friend before making the choice to purchase.

Breast Pump Flange Size

Manufacturing companies typically have flange sizes available between 21mm and 30mmm. There are bigger flange sizes made for women with larger nipples, but these would need to be specially ordered and may not fit all pumps.  It is generally recommended that you choose a flange size slightly larger (about 2- 4 mm) than your nipple diameter. You will obviously need to work with what is available. If you are unsure you can start expressing with the standard size that comes with the breast pump, and then up- or downsize if needed.

BabyWombWorld Flange Size Table

How to measure your nipple

With a ruler or measuring tape, measure the diameter of your nipple (do not include the areola).

how to measure your nipple

Your nipple size changes in pregnancy so you may want to wait until you actually start expressing before doing this. In some breastfeeding women it may also change over time, so if you start experiencing problems you should recheck the fit. This is only likely to be an issue if your fit was borderline in the first place.  Occasionally you may even need different flange sizes for your two nipples.

ALSO READ: Top 5 Things You Need for Breastfeeding

How do you know if the breast pump flange fits?

Observe your nipple during pumping. Your whole nipple should comfortably pull into tunnel with a small space around. If the sides of the nipple rub against the sides of the tunnel the flange is too small. If too much of the areola gets pulled in the size may be too large. This will lead to the pump losing suction and to your nipple ‘bouncing’ back at the end of every cycle.

Flange Size Information Sheet Download

Signs of an ill-fitting flange include:

  • Pain during expressing – with BabyWombWorld’s 3D suction technology the nipple gets ‘massaged’ during suction, one of the reasons why so many women experience better pumping and higher milk volumes with the BabyWombWorld electric pumps. This yields a different sensation than a nipple simply being pulled into a flange tunnel with other breast pumps. However, pumping should still not be sore, so if you experience pain that doesn’t improve when lowering the suction, suspect the flange.
  • A nipple that looks blanched, have rub marks or cuts, or have a white ring at its base after expressing.
  • Lumps/full areas in the breast after an expressing session – this can lead to blocked ducts and mastitis.
  • Struggling to maintain a vacuum during expressing – to compensate for this, women will often press the flange harder into their breasts while expressing. This can cut of milk flow and also lead to blocked ducts.
  • Lastly, an ill-fitting flange will lead to lower milk volumes and to lowered milk supply over a period of time.

READ MORE: How to choose a breast pump

Sometimes you may need to experiment before finding what works best. Remember that the cost of a different size flange still pales in comparison to the cost of formula feeding. It’s worthwhile making sure that you are expressing as effectively as possible to keep offering your baby the best milk there is.

Christine Klynhans is a midwife and lactation consultant with a firm believe that gentle parenting can change the world. She has worked in midwifery since competing her B.Cur nursing degree in 2004, and has a special passion for education and for writing. She currently works in a well-baby clinic and give antenatal classes and breastfeeding support. She enjoys working with parents of babies and toddlers, aiming to help them find gentle solutions to their parenting problems and assisting them in incorporating healthy habits and natural health alternatives into their daily lives.

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