Correctly Fitting Breast Shields

Irene Murphy Zoppi, RN, MSN, IBCLC / September 2016


Mothers use breast pumps for many reasons. Most often, mothers pump on a regular basis to provide breast milk for their preterm or hospitalized infants, or when they are working outside of the home.  A mother’s breast pump equipment should help protect her milk volume by optimizing breast emptying, preventing nipple trauma, and providing maximum comfort while pumping, all of which can be achieved by using a correctly-sized breast shield. But one out of three mothers pump with incorrectly fitted breast shields, and many mothers and professionals do not know how to correctly size breast shields.

Breast shields are the only component of the breast pumping system that come in direct contact with the mother’s nipple and breast. Because of the wide variation between breast and nipple shapes and sizes, a one-sized breast shield doesn’t fit all women. Breast shield fitting involves a balance between a clinical fit of the shield to the mother’s breast, milk output, and mother’s comfort. It also involves an understanding of the anatomy of the lactating breast.

The ultrasound research findings published by Dr. Donna Geddes in 2005 demonstrated the location and fragility of the ductal system.1 Her research identified that milk ducts are located under the nipple and areola areas, are very easily compressible, and do not store milk; milk ducts collect milk, allowing transport to the nipple for removal. The research also acknowledged that a majority of glandular tissue, the segment of the mammary gland where milk is synthesized and stored, is located within a 30mm radius of the nipple and areola areas, and can be located very close to the skin surfaces of the breast. Due to the compressibility of the milk ducts and the location of both the ductal and glandular tissue, it is imperative that breast shields properly fit. A breast shield that is either too small or too large can affect milk flow and subsequent emptying of the breasts.

Medela PersonalFit™ Breast shields are available in multiple sizes to accommodate the anatomical differences in nipple sizes among women.  Knowing how to select a correct size breast shield for each pumping mother is critical to her pumping success—yet this is an aspect of using a breast pump that is challenging to mothers.

Visible inspection alone of the diameter and/or length of a mother’s nipple is inadequate in determining correct breast shield sizing.  The nipple is comprised of elastic tissue that is capable of stretching and elongating. The vacuum generated by the breast pump will cause nipple stretching similar to what occurs when a healthy infant breastfeeds. After measuring the mother’s nipple, the assessment process should continue with watching the mother pump, to visualize how her nipples respond to the vacuum applied by each cycle of the pump, and how her nipples are drawn into the breast shield tunnel. It is also important to ask the mother for feedback on how pumping feels to her. It may be necessary to experiment with multiple breast shield sizes to find a suitable fit.

Based on feedback received from focus groups of pumping mothers, and their ability to correctly assess their own breast shields, we developed this sizing tool for mothers and clinicians. It involves measuring the mother’s nipple and watching her pump to visualize how her anatomy responds to the cycling and suction vacuum of the pump.

You can download it here.

For more information and instruction on breast shield sizing, you can watch our complete one-hour recorded webinar, ‘Fitting Breast Shields: Determining the Correct Breast Shield Size’. (Use promo code XD2HDT to save $15 through October 31, 2016.)

In summary, an understanding of breast anatomy and knowledge of the breast changes during lactation informs proper breast shield selection and fitting. A correctly fitted breast shield will protect maternal milk volume, optimize breast emptying, prevent nipple trauma, and maximize comfort during pumping.

Share your experience with us in the comments section below: How do you educate mothers on breast shield fit?


  1. Ramsay et al. Anatomy of the lactating human breast redefined with ultrasound imaging. J Anat. 2005; 206(6):535-35


About the Author

Irene joined Medela in 1999 as a clinician for the Breastfeeding Division. She currently serves as a Clinical Education Specialist focusing on Advocacy Outreach. In this role, she acts as a vital resource for groups assisting breastfeeding mothers and infants. She has been frequently interviewed on radio and online regarding breastfeeding issues for mothers and clinicians.

Irene spent many years caring for new families in antenatal, labor and delivery, postpartum and NICU settings and was involved in direct patient care and family-based education. Irene has extensive experience teaching in a variety of nursing education programs.  She produced a video presentation on nursing students’ involvement in Community Health Nursing for the National League of Nursing.