A Novel method for quantifying fluctuations in wearable derived daily cardiovascular parameters across the menstrual cycle.

Currently, knowledge of changes in cardiovascular function across the menstrual cycle and how these changes may inform upon underlying health is limited. Utilizing wrist-worn biometric data we developed a novel measure to quantify and investigate the cardiovascular fluctuation (i.e. cardiovascular amplitude) within resting heart rate (RHR) and heart rate variability (RMSSD) across 11,590 participants and 45,811 menstrual cycles. Within participants, RHR and RMSSD fluctuated in a regular pattern throughout the menstrual cycle, with population RHRmin and RMSSDmax at cycle day 5, RHRmax at day 26, and RMSSDmin at day 27. Cardiovascular amplitude was attenuated (p < 0.05) in older participants and participants using birth control, suggesting the novel metric may mirror differences in hormonal fluctuations in these cohorts. Longitudinal tracking of cardiovascular amplitude may offer accessible non-invasive monitoring of female physiology and underlying health across the menstrual cycle.