Heart rate variability during high and low estrogen during the menstrual cycle

To determine whether heart rate variability changes due to varying levels of estrogen, we studied nine women during menses, i.e. the lowest level of estrogen, and during the peak estrogen level that occurs during the follicular phase. Welch´s method was used to calculate the power spectral density. Low and high frequency power were calculated in the appropriate spectral bands. We found that neither low nor high frequency power changed significantly across the two phases studied. High frequency power as compared to low frequency power was significantly higher during both menses and the follicular phase.