Detection of Milk Ejection Using Bioimpedance Spectroscopy in Lactating Women during Milk Expression Using an Electric Breast Pump

  • Hazel GardnerEmail author
  • Ching Tat Lai
  • Leigh Ward
  • Donna Geddes


Milk ejection is essential for effective milk removal during breastfeeding and pumping, and for continued milk synthesis. Many women are unable to accurately sense milk ejection to determine whether their infant is receiving milk or, when pumping, to switch the pump to a more effective expression pattern. To determine if changes in bioimpedance parameters are associated with milk ejection in the lactating breast during pumping. 30 lactating women participated in 2 pumping sessions within 2 weeks of each other. During pumping the breasts were monitored with bioimpedance spectroscopy (on either the pumped or the non- pumped breast), and milk flow rate and volume were measured simultaneously. All mothers completed 24-h milk productions. Linear mixed effects models were used to determine associations between milk flow rate and bioimpedance changes. Changes in bioimpedance parameters were greater at the first milk ejection when measured on the pumped breast (median (IQR): R zero: −7 (−17, −4,) % (n = 30); R infinity: −8 (−20, −2) % (n = 29); membrane capacitance: −24 (−59, −7) % (n = 27). Changes in bioimpedance detected in the non-pumped breast were lower at the first milk ejection, R zero: −3 (−8, −2) % (n = 25); R infinity: −5 (−8, −2) % (n = 23); membrane capacitance: −9 (−17, 15) % (n = 24). Smaller less consistent decreases in the bioimpedance characteristics were detected at the second milk ejection in both breasts. Bioimpedance parameters showed a consistent decrease associated with the first milk ejection when electrodes were placed on the pumped breast. Smaller decreases were observed when the non-pumped breast was monitored for the first and second milk ejection. There was wide variation in the magnitude of changes observed, and hence further development of the methodology is needed to ensure reliability.


Lactation Breast Bioimpedance Milk ejection 



This research was funded by an unrestricted research grant from Medela, Ag, Baar Switzerland .

The authors would like to thank the participants, and the Australian Breastfeeding Association (WA Branch) for their support (Approval 2016-1).

Compliance with Ethical Standards

HG, CTL & DG are supported by an unrestricted research grant from Medela AG.

The study was approved by The University of Western Australia Human Research Ethics Committee (RA/4/1/7897).

All participants provided written informed consent.

Conflicts of Interest

Author Ward provides consultancy services to ImpediMed Ltd. ImpediMed had no input into the conception or conduct of the study or the writing of the manuscript.


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© Springer Science+Business Media, LLC, part of Springer Nature 2019

Authors and Affiliations

  1. 1.School of Molecular Sciences, Faculty of ScienceUniversity of Western AustraliaPerthAustralia
  2. 2.School of Chemistry and Molecular SciencesUniversity of QueenslandBrisbaneAustralia

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