Flange Sizing and Its Impact on Pumping and your Milk Supply

For many new parents, pumping becomes an essential part of their breastfeeding journey. Whether you're exclusively pumping by choice, or situation (you have a premature or medically fragile baby), working, or supplementing with formula, having the right tools are important to ensure that your experience is as comfortable and efficient as possible.

One of the most important pieces of equipment you'll use is the pump flange. Most people are using a flange that is way too big for them. Pumps typically come with standard size flanges (24 mm and or 28mm). The most common size nipple during the recently published study was found to be much smaller, around 15/17mm. In our practice, the average nipple size we see is about 13/15mm.

As lactation consultants, we've seen first-hand the impact that correct flange sizing can have on both milk output, comfort and pumping session time to fully empty. Unfortunately, it’s also a very common issue that many new parents overlook. Flange sizing is not a one-size-fits-all process, and finding the right fit for your body is essential. Here's why it matters and how you can ensure you're using the correct size for your unique needs.

Why Flange Size Matters

The flange is the part of the pump that fits over your nipple during pumping. When the flange is the right size, it helps facilitate effective milk removal and minimizes the risk of pain or injury to the nipple and surrounding breast tissue. But if the flange is too small or too large, it can cause several issues, including:

• Ineffective Milk Removal: If the flange is too small, your nipple will not move freely into the tunnel and can interfere with milk flow. On the other hand, a flange that’s too large may pull too much of the areola into the tunnel, and cause compression of milk ducts and not effectively remove milk. Ineffective milk removal can lead to engorgement.
• Pain and Discomfort: A poor fit can lead to nipple pinching, chafing, swelling or bruising, making the whole pumping process feel uncomfortable. Pain can decrease the flow of hormones needed to let milk flow. Over time, this can also contribute to damaged tissue and let’s face it; nobody wants to do something if it hurts! Damage to nipples can possibly lead to mastitis, and engorgement from decreased milk removal.
• Reduced Milk Supply: When milk is not being effectively expressed, it can send signals to your body that less milk is needed, leading to a decrease in overall milk supply. This is especially concerning for parents who are pumping to build or maintain a supply.
• Emotional Impact: Pumping with an ill-fitting flange can be frustrating, painful, and discouraging. It’s important for parents to know that there are solutions to this problem.

How Do You Know If Your Flange Size Is Correct?

• Comfort: You should not feel pain or discomfort during the pumping session. You might experience a pleasurable sensation or a mild sensation of gentle tugging or pulling, or no sensation; but nothing should feel sharp, tight, stinging or “pinchy”.
• Nipple Movement: When pumping, your nipple should gently glide, while touching the sides of the tunnel.  Ideally, only the nipple should be pulled into the tunnel, moving freely while the areola remains unaffected. If the nipple is not stretching or moving freely, your body may not be able to trigger a let-down. Since nipple stretching is what triggers the let-down, a lack of movement may prevent milk from flowing.
• Milk Flow: Milk should flow smoothly and steadily during pumping. You should see sprays of milk.

How do I find out what my correct size is?

Schedule a Flange fitting/Pumping consultation with us or another lactation consultant trained in flange fitting.

A flange fitting appointment includes a pumping trial using multiple shapes and sizes of flanges during a pumping session to find the optimal fit.

These sessions can be invaluable, especially if you're struggling with discomfort or low milk output. A professional fitting can also help you learn more about how to use your pump effectively, and they can help troubleshoot issues related to pumping efficiency and supply.

If you prefer to figure it things out on your own, read this Flange FITS Guide, from Babies in Common. It comes with and explanation of how to size and fit. If you print it out there is a ruler you can use to measure your nipples.