Finding the right breast pump flange size is a common concern for new parents, and it is a simple step that greatly influences your pumping experience. The flange, which is the funnel-shaped piece of plastic that fits over the nipple and areola, must be the correct diameter to work properly. Ensuring an accurate measurement is the first and most effective way to maximize comfort and efficiency when using a breast pump.
Why Correct Flange Sizing Is Essential
Using the wrong size breast pump flange leads to inefficiency in milk expression and causes physical discomfort. Correct sizing ensures only the nipple is drawn into the flange tunnel during suction, allowing it to move freely without rubbing against the sides.
If the flange is too small, the nipple rubs and chafes against the tunnel wall, causing friction, irritation, and pain. This friction can lead to damage like blistering, soreness, or nipple blanching, where the nipple turns white due to restricted blood flow.
A flange that is too large pulls in too much of the areola along with the nipple, causing swelling and pain. This excessive pulling compresses the milk ducts beneath the areola, hindering milk flow and preventing the breast from fully draining.
Ineffective milk removal can signal the body to produce less milk, potentially reducing the overall supply over time. Proper sizing ensures the pump works effectively, resulting in more milk expressed in a shorter time while keeping the breast tissue healthy.
Optimal Timing for Nipple Measurement
The timing of nipple measurement is important because the size can change under various conditions. Measuring during pregnancy is often inaccurate because hormonal changes and swelling temporarily alter breast tissue size. Similarly, measuring immediately postpartum may not yield a true size due to initial swelling or engorgement.
For the most accurate baseline measurement, wait until your milk supply has regulated and initial swelling has subsided, typically a few weeks postpartum.
A precise method involves measuring after the nipple has been stimulated, mimicking the size it will be when actively pumping. Measure after a brief, gentle pumping session or after manually stimulating the nipple to encourage it to become firm. This accommodates the slight expansion that occurs during milk extraction. Since nipple size can fluctuate, measure at a consistent time, such as just before a scheduled pumping session.
Step-by-Step Measurement Methods
To accurately determine your ideal flange size, measure the diameter of your nipple in millimeters (mm). Use a ruler, flexible measuring tape, or a specialized printable nipple ruler with millimeter markings, as flange sizes are always listed in millimeters. Measure both nipples independently, as it is common to require a different size for each breast.
The measurement must be taken across the base of the nipple, focusing solely on the protruding part, not the surrounding areola. Measure the diameter at the widest point where the nipple meets the areola, recording the number in millimeters.
After measuring the diameter, add 2 to 4 mm for clearance, which allows the nipple to move freely inside the flange tunnel without friction. For example, a nipple measuring 17 mm would pair with a 21 mm flange to allow for necessary expansion and movement.
Recognizing and Addressing Poor Flange Fit
Even with careful initial measurement, the fit may not be perfect, so you must recognize the signs of a poor flange fit. A too-small flange causes the nipple to rub painfully against the sides of the tunnel, and the nipple may appear compressed or white (blanched) upon removal due to restricted circulation.
A flange that is too large pulls excessive areola tissue deep into the tunnel. If the breast still feels full or heavy after pumping, it indicates incomplete drainage.
If you experience pain, a change in nipple color, or a significant drop in milk output, consider re-measuring your nipples. Nipple size can change throughout your pumping journey, so a previous size may now be inaccurate. Trying the next size up or down is a simple adjustment to test for better comfort and output. For micro-adjustments between standard sizes, explore silicone flange inserts, which reduce the tunnel size inside a larger hard flange.