A breast pump flange, also known as a breast shield, is the funnel-shaped component that forms a vacuum seal around the nipple and areola during a pumping session. This seal generates the suction required to draw the nipple into the tunnel and extract milk effectively. Using the correct flange size is paramount for both comfort and maximizing milk yield, as an incorrect fit can restrict milk flow and cause significant discomfort. The process of finding the right size can feel confusing for new users, especially when faced with many different options.
Understanding Flange Sizing and the Concept of Average
The most common flange sizes included with breast pumps are typically 24 millimeters (mm) and sometimes 27 mm. This leads many to believe these sizes represent an “average” fit, but this is based on manufacturing standards, not a comprehensive anatomical survey. The actual range of flange sizes available spans widely, often from 10 mm to 40 mm, indicating the vast difference in individual nipple sizes. Nipple size is highly individual and has no correlation with breast size.
A generalized average size is irrelevant to an individual’s pumping needs. Using a flange that is too small or too large causes inefficient milk removal, pain, and potential damage to the nipple tissue. Nipple size can also change over time, fluctuating during the lactation journey, swelling during a pumping session, or differing between the left and right breast. Relying on a single “average” size is not advisable for comfortable and productive milk expression.
Step-by-Step Guide for Accurate Nipple Measurement
Accurately measuring the nipple diameter is the most reliable method for determining the proper flange size. The measurement should be taken before a pumping session, as stimulation or pumping can temporarily increase the nipple size. A millimeter ruler, flexible measuring tape, or specialized nipple measuring tool should be used, as flange sizes are standardized in millimeters.
The measurement must focus exclusively on the diameter of the nipple base, where the nipple meets the areola, and should not include the areola itself. Gently stimulate the nipple beforehand to encourage it to become firm, ensuring the measurement reflects the actual size. It is important to measure both nipples independently, as it is common to require two different flange sizes.
Once the nipple diameter measurement is obtained, the correct flange size is calculated by adding a small buffer. Lactation experts suggest adding 2 mm to 4 mm to the nipple measurement to account for comfortable movement and natural swelling during pumping. For example, a nipple measuring 17 mm would generally need a 21 mm flange, which includes a 4 mm buffer. This extra space prevents friction and allows the nipple to move freely inside the flange tunnel.
The final step involves test-fitting the calculated flange size to ensure the nipple is centered and moves gently within the tunnel. Regular remeasurement may be necessary if pain occurs, or if there are changes in milk output or nipple appearance, as the required size can fluctuate.
Visual and Physical Signs of Incorrect Flange Fit
An improperly sized flange causes pain, significantly reduces milk expression, and can lead to complications like clogged milk ducts. The symptoms of a poor fit can be separated based on whether the flange is too small or too large.
If the flange is too small, the most common sign is the nipple rubbing uncomfortably against the sides of the tunnel during the suction cycle. This friction leads to tenderness, pain, and visible damage such as bruising or cracking at the nipple base. Additionally, the nipple may appear white or blanched after pumping, indicating that the blood supply has been temporarily constricted.
When a flange is too large, an excessive amount of the areola is pulled deeply into the flange tunnel along with the nipple. This causes a painful tugging sensation and may result in the areola appearing bruised or swollen after the session. A flange that is significantly too big may also fail to create a proper vacuum seal, leading to inefficient milk expression and a reduction in milk output. In both cases of improper fit, the breast may not feel fully drained after pumping, signaling that the milk ducts are not being stimulated effectively.