Heart Rate Variability Changes Across Menstrual Phases in Young Adults: An Autonomic Perspective

A BSTRACT Introduction: The menstrual cycle represents the intrinsic physiological rhythm experienced by females throughout their reproductive years. This intricate interplay of hormones orchestrates a profound influence on individuals, exerting substantial effects on both their physical well-being and emotional state. The menstrual cycle could also affect their degree of stress and autonomic functions which was not studied in detail. Therefore, this study aims to assess the changes in heart rate variability (HRV) during the menstrual, proliferative, and secretory phases of the menstrual cycle. Materials and Methods: Twenty-two female subjects aged 18–25 years with regular menstrual cycles were included in the study. The HRV was recorded thrice within a single menstrual cycle and the stress levels of the subject during the menstrual phase were assessed using a perceived stress scale (PSS) questionnaire. Results: The time domain parameters SDNN, NN50, pNN50, and RMSSD progressively decreased in the proliferative and secretory phases compared to the menstrual phase ( P < 0.05). The mean RR interval decreased and the mean HR increased significantly in the secretory phase compared to the menstrual phase ( P < 0.05). The PSS score during the menstrual phase was found to be 20.50 ± 2.35. Conclusion: Time domain parameters of HRV show a progressive decrease from day 1 to day 20 of the menstrual cycle. This pattern underscores a tilt of autonomic balance towards the sympathetic predominance as the cycle progresses from the menstrual phase to the secretory phase.