The breast pump flange is the funnel-shaped piece of plastic or silicone that fits over the breast to create a vacuum seal. This seal is necessary to draw the nipple into the flange tunnel and extract milk during a pumping session. A proper fit ensures comfort, prevents nipple damage, and maximizes the amount of milk expressed efficiently. Using a flange that is too large or too small can lead to pain, clogged milk ducts, and lower milk output. Finding the correct flange size requires both an initial measurement and close observation during pumping.
Determining Your Starting Flange Size
Finding the right flange starts with accurately measuring the nipple’s diameter before pumping or nursing. To get this baseline measurement, gently stimulate the nipple until it is erect. Use a ruler or measuring tape to find the diameter in millimeters across the base where the nipple meets the areola, measuring only the nipple tissue.
Since nipple sizes can differ, measure both breasts separately. This measurement provides the diameter of the tissue that will be drawn into the tunnel, but it is not the final flange size. Most professionals recommend adding 2 to 4 millimeters to the measured diameter to determine a starting flange size, allowing for the natural swelling that occurs during pumping.
For example, a nipple measuring 17 millimeters suggests a starting flange size of 20 to 21 millimeters. This calculated size serves as a reference point for selecting a flange to test during a pumping session. If pumping becomes uncomfortable or less effective, re-measure, as nipple size can change, especially in the first few weeks postpartum.
Visualizing a Proper Fit During Pumping
Once the pump is turned on, the visual and physical cues of a correct fit should guide confirmation. A correctly sized flange allows the nipple to move freely and centrally within the tunnel with each suction cycle. The nipple should glide back and forth gently, without rubbing or sticking to the sides of the tunnel walls.
Only the nipple, and perhaps a very small amount of the areola, should be drawn into the flange tunnel. Seeing only 1 to 2 millimeters of areola pulled in with the nipple is a good indicator. The pumping session itself should feel comfortable, with a noticeable tugging sensation but no sharp, pinching, or burning pain. Milk should flow efficiently in strong streams or sprays, indicating effective milk removal.
After the session, the nipple should look healthy, with no significant swelling or lasting discoloration. While the nipple may appear slightly longer due to the stretching action of the pump, its width at the base should be the same as before pumping. The breasts should feel soft and adequately drained, which signals efficient milk extraction.
Identifying Signs of an Incorrect Fit
Observing negative signs during or after a session indicates the flange size is incorrect. If the flange is too small, the nipple rubs against the sides of the tunnel, causing friction and pain. This misalignment often leads to the nipple tip blanching, or turning white, which is a sign of restricted blood flow.
Other symptoms of a flange that is too small include:
- Bruising or redness.
- A feeling that milk ducts are blocked.
- Significantly reduced milk output.
If the flange is too large, an excessive amount of the areola is pulled deep into the tunnel with the nipple. This can cause a painful tugging sensation on the breast tissue and may lead to swelling or soreness around the areola. Although a large flange may feel less painful initially, it results in low milk yield because the pump does not stimulate the milk ducts effectively.
Signs that the flange is too large include:
- A visible ring of chafed skin around the areola.
- The breast still feeling full after a completed session.
- Low milk yield despite adequate pumping time.
Adjustments and Next Steps for Better Fit
If a session reveals an incorrect fit, adjust the size, typically moving in small 2-millimeter increments. If the current flange is too tight, increase the size by 2 millimeters; if it is too loose, decrease the size. Test the new size immediately to assess comfort and milk flow.
For individuals whose nipple size falls between standard measurements, silicone flange inserts can provide a customized fit. These inserts are placed inside a larger flange to reduce the tunnel size, allowing for more precise sizing. If discomfort persists or milk output remains low, consulting with an International Board Certified Lactation Consultant (IBCLC) is recommended for personalized advice.