Correlation between heart rate variability and estradiol, progesterone, and the estradiol/progesterone ratio across menstrual phases in healthy women

Heart rate variability (HRV) is widely used to assess cardiac health, yet uncertainty persists regarding HRV variations across the menstrual cycle and their association with reproductive hormones. Few studies have evaluated the full spectrum of HRV parameters, and most estimated menstrual phases from the last menstrual period without considering individual cycle length. This study aimed to compare HRV parameters across three menstrual phase groups, using accurate cycle tracking based on the next menstrual period and actual cycle length, and to correlate HRV with estradiol, progesterone, and the estradiol/progesterone (E/P) ratio. In 112 healthy women with regular cycles, HRV parameters were measured using a heart rate sensor, and serum hormone levels were obtained. Menstrual phase groups were defined using back-extrapolation from the next cycle. Data from 99 participants were analyzed: menstruation (n = 38), periovulatory (n = 30), and premenstrual phase (n = 31). HF was significantly higher during the peri-ovulatory phase, while estradiol and progesterone peaked premenstrually. The E/P ratio was highest pre-ovulatory. Estradiol correlated with most HRV measures; however, only the mean RR-interval in the premenstrual phase was statistically significant, with estradiol emerging as a negative independent predictor. These findings conclude notable HRV variation across menstrual phases and suggest that estradiol fluctuations may influence autonomic regulation.