A breast pump flange, also known as a breast shield, is the funnel-shaped component that forms a seal around the nipple and areola during milk expression. It connects the breast to the pump’s motor, creating the vacuum necessary to draw milk. Using the correct size flange is important because it directly influences both comfort and the efficiency of milk extraction. The wrong fit can lead to pain, tissue damage, and a reduction in milk production.
Finding Your Starting Flange Size
Determining a starting flange size requires measuring the diameter of the nipple base before a pumping session begins. The measurement must focus only on the nipple’s width at the point where it meets the areola, not including the areola itself. This initial measurement should be taken when the nipple is relaxed or after gentle stimulation, using a ruler or measuring tool.
The flange size chosen should be slightly larger than the measured diameter of the nipple to allow for movement during pumping. Selecting a flange that is approximately 2 to 4 millimeters larger than the nipple base diameter is a guideline. For example, a nipple measuring 16 mm across would typically require a 21 mm flange. This difference provides space for the nipple to be drawn freely into the tunnel without excessive friction.
This measurement only provides a static starting point for flange selection. Since nipple size can vary, it is best to measure both nipples separately. The true test of a proper fit depends entirely on the dynamic movement and comfort experienced once the pump is actively running.
Observing Ideal Nipple Movement During Pumping
Once the pump is in use, the appearance of the nipple inside the flange tunnel provides the most accurate feedback on the fit. The nipple should be centered within the tunnel and move back and forth in a smooth, rhythmic motion. This movement must be unrestricted, meaning the nipple should glide freely without rubbing or sticking against the sides of the tunnel.
During the vacuum phase of the pump cycle, the nipple should be drawn deeply into the tunnel, often elongating to reach about two-thirds to three-quarters of the tunnel length. Only a minimal amount of the areola should be pulled in; the primary tissue pulled in should be the nipple.
The sensation during pumping should be comfortable, involving a gentle tugging feeling but never sharp pain. A good fit ensures the vacuum seal is effective, which maximizes milk removal and helps fully drain the breast. After the session, the nipple may appear longer, but it should not be swollen, discolored, or bruised.
Practical Indicators of Poor Flange Fit
Flange is Too Small
Using a flange that is too small often results in the nipple rubbing against the tunnel walls during the pumping cycle. This friction can cause pain, chafing, and skin breakdown, sometimes resulting in cracks or bruising at the base of the nipple. Another indicator of an undersized flange is when the nipple tip repeatedly hits the end of the tunnel, restricting full extension.
When the flange is too tight, it can compress the milk ducts located at the base of the nipple, blocking the flow of milk. This duct compression hinders the complete release of milk, which can lead to a feeling of incomplete emptying and a decrease in milk output. In severe cases, restricted blood flow can cause the nipple to turn white, a sign known as blanching, which requires immediate attention.
Flange is Too Large
If the flange size is too large, excessive areola tissue is pulled into the tunnel along with the nipple. This excessive pull subjects the areola and surrounding breast tissue to friction, leading to swelling and soreness after the session. The vacuum seal may also be compromised, resulting in air leaks and a less effective pump performance.
A flange that is too large can create a ring of redness, similar to a hickey, around the base of the nipple where the areola was pulled in. This tissue trauma can lead to swelling and bruising, and often results in reduced milk output. Persistent pain, discomfort, or a feeling that the breasts remain full after pumping are signals that the current size is incorrect and needs immediate adjustment.