A breast pump flange, often called a breast shield, is the funnel-shaped component that fits over the nipple and areola, creating a seal for milk extraction. Most breast pumps are sold with a standard 24 millimeter (mm) flange, but nipple sizes vary widely, making this one-size-fits-all approach frequently incorrect. Determining the correct flange size is necessary for comfortable and effective milk expression. The flange size refers to the diameter of the tunnel the nipple enters. This measurement must allow the nipple to move freely without friction during pumping.
Why Correct Flange Sizing Is Crucial
Using an incorrectly sized flange can lead to physical health problems and reduced milk output. If the flange is too small, the nipple can rub painfully against the tunnel walls, leading to friction, abrasion, and potential trauma. This friction can result in cracked nipples, bruising at the base of the nipple, and discoloration, making the pumping experience highly uncomfortable.
An improper fit also severely impacts the efficiency of milk expression and milk supply. A flange that is too small can constrict tissue, preventing milk ducts from fully draining and potentially causing clogged ducts. If the flange is too large, it can pull in too much of the areola, compressing milk ducts. This incomplete drainage signals the body to reduce milk production.
Step-by-Step Guide to Measuring Nipple Diameter
The first step involves measuring the nipple diameter in its natural state, before a pumping session. Wait at least 30 minutes after breastfeeding or pumping to ensure the nipple is relaxed and not swollen or erect. Using a ruler or a measuring tape marked in millimeters (mm) is the most accurate tool for this measurement.
The measurement must focus exclusively on the diameter of the nipple at its base, where it meets the areola. Do not include any of the areola tissue itself. Place the ruler horizontally across the widest part of the nipple and record the measurement in millimeters. It is important to measure both nipples, as they often require different flange sizes.
Once the nipple diameter is recorded, a buffer must be added to allow for natural expansion during pumping. The general recommendation is to add 2 to 4 mm to the measured diameter to determine the starting flange size. For example, an 18 mm nipple diameter suggests trying a flange size between 20 mm and 22 mm.
Assessing the Fit During Pumping
The measurement provides a starting point, but the true fit must be confirmed by observing the nipple while the pump is running. A correctly sized flange allows the nipple to be drawn into the tunnel, centered, and move freely without rubbing against the sides. Only a small amount of the areola should be pulled into the tunnel along with the nipple.
Signs of a poor fit are evident during the pumping action itself. If the flange is too small, the nipple may rub and cause pain, or appear white or blanched after the session due to restricted blood flow. A flange that is too large pulls in a significant portion of the areola, causing discomfort or a pinching sensation. If the breasts still feel full or heavy after pumping, the flange is likely not draining the breast effectively.
Factors That Influence Size Changes
Nipple size is not static, and the flange size will likely need to be re-evaluated over time. Hormonal fluctuations and postpartum swelling commonly affect size in the initial weeks after childbirth. Nipple size often increases immediately postpartum and then gradually decreases as hormones settle and swelling subsides, typically within the first 6 to 12 weeks.
Changes in nipple elasticity can also influence the required flange size, particularly with long-term or frequent pumping. The material and design of the pump can also affect the fit, as different pump brands or types of flanges may require slight adjustments to the size. For these reasons, if pumping becomes uncomfortable or milk output noticeably decreases, the nipple should be re-measured to ensure the flange continues to provide an optimal fit.