The development and validation of an activity monitoring system for use in measurement of posture of childbearing women during first stage of labour Precis: An activity monitoring system was validated to measure posture of women during labour and effects upon length of first stage, pain experience and birth satisfaction. Abstract Introduction: There is limited understanding of the type and extent of maternal postures that midwives should encourage or support during labour. The objective of this study was to develop an activity monitoring system existing commercial activity monitors to measure posture and movement. The aims were to identify a set of postures and movements commonly seen during labour, to develop an activity monitoring system for use during labour, and validate this system design. Methods: Volunteer student midwives simulated maternal activity during labour in a laboratory setting. Participants (n=15) wore monitors adhered to the left thigh and left shank, and adopted13 common postures of labouring women for 3 minutes each. Simulated activities were recorded using a video camera. Postures and movements were coded from the video and statistical analysis conducted of agreement between coded video data and outputs of the activity monitoring system. Results: Excellent agreement between the two raters of the video recordings was found (Cohen’s Kappa 0.95). Both sensitivity and specificity of the activity monitoring system were over 80% for standing, lying, kneeling and sitting (legs dangling). Discussion: This validated system can be used to measure elected activity of labouring women and report on effects of postures upon length of first stage, pain experience, birth satisfaction and neonatal condition. This validated maternal posture monitoring system is available as a reference and for use by researchers who wish to develop research in this area. Keywords: birth, first stage, movement, posture, ActivPAL,
13. Cohen J. A coefficient of agreement for nominal scales. Educational and Psychological Measurement 1960;20:37-46. 14. Frenea S, Chirossel C, Rodriguez R. The effects of prolonged ambulation on labor with epidural analgesia. Obstetric Anesthesia2004;98:224-229. 15. Karraz MA. Ambulatory epidural anaesthesia and the duration of labour. International Journal of Gynecology and Obstetrics 2003;80:117-122. 16. MacLennan AH, Crowther C, Derham R. Does the option to ambulate during spontaneous labour confer any advantage or disadvantage? Journal of Maternal andFetal Medicine1994;3:43-48. 17. Godfrey A, Culhane KM, Lyons GM. Comparison of the performance of the activPAL™ Professional physical activity logger to a discrete accelerometer- based activity monitor. Medical Engineering & Physics 2007;29:930-934. 18. Grant PM, Dall PM, Mitchell SL, Granat MH. Activity-monitor accuracy in measuring step number and cadence in community-dwelling older adults. Journal of Aging and Physical Activity2008;16:201-14. 19. Ryan C, Gray H, Newton M, Granat MH. The convergent validity of free-living physical activity monitoring as an outcome measure of functional ability in people with chronic low back pain. Journal of Back and Musculoskeletal Rehabilitation 2008;21:137-142. 20. Mickelborough J, Kenney L, Moss S.Validation of a novel activity monitor. Proceedings Recent Advances in Assistive Technology and Engineering (RAATE).Conference, Birmingham, UK,10-11:2003. (Supporting Information: Appendix S1): Histograms showing frequency of rating by (n=95)