Sympathetic nervous system control across the menstrual cycle

The menstrual cycle is characterized by fluctuations in ovarian hormones that influence the regulation of physiological systems, including homeostatic adjustments in cardiovascular control. The sympathetic nervous system maintains refined control over cardiovascular homeostasis through adjustments in systemic and local hemodynamics, and via neural reflexes and sympathetic neurovascular transduction. However, the extent to which these autonomic pathways are modulated by endogenous hormonal shifts remains a significant knowledge gap. This narrative review consolidates current evidence on autonomic function across the menstrual cycle, with a focus on muscle sympathetic nerve activity, sympathetic neurovascular transduction, sympathetic neural reflexes, and heart rate variability. Additionally, we briefly explore the influence of exogenous hormone use, primarily oral contraceptive pills, on autonomic regulation. A critical and often overlooked distinction in the literature is that while resting sympathetic drive is significantly elevated during the mid-luteal phase, the sensitivity of most neural reflexes remains functionally stable. This stability suggests that the mid-luteal surge in estradiol acts as a vital vascular buffer, enhancing sympatholysis and nitric oxide bioavailability to offset the increase in underlying neural drive. We further examine exceptions to this stability, specifically the peripheral chemoreflex, and explore the impact of exogenous hormones on neurovascular homeostasis. Characterizing these interactions is essential for understanding physiological and pathophysiological changes across the female lifespan.