Heart rate variability during different phases of menstrual cycle

The purpose of the present study was to determine whether there is a menstrual cycle effect on heart rate variability. Ten healthy regularly cycling females (age 19-23 years) were studied during the follicular phase (FP) and luteal phase (LP) of menstrual cycle over two month. We found significant changes in heart rate (65,35±0,68 beats/min in FP vs 73,18±0,92 beats/min in LP, p<0,0005), AMo and stress index during the menstrual cycle with a minimum in the follicular phase (36,81±1,14 % and 76,86±5,74 p.d.u. respectively) and maximum in the luteal phase (42,05±1,27 % and 107,70±7,77 p.d.u. respectively, p<0,003). The HF and LF components decreased more during the luteal phase (655,56±46,64 ms2 and 981,85±66,64 ms2 respectively) than during the follicular phase (997,42±83,36 ms2 and 1524,66±145,17 ms2 respectively, p<0,05). In the follicular phase SDNN, pNN50, MxDMn were significantly higher (0,057±0,002 s, 41,49±1,79 % and 0,333±0,012 s respectively) than in the luteal phase (0,051±0,002 s, 29,73±1,88 % and 0,303±0,012 s respectively, p<0,05). Furthermore, the VIK was higher in the luteal phase compared to the follicular phase (p=0,003). These findings indicate that sympathetic nervous activity in the luteal phase is greater than in the follicular phase, whereas parasympathetic nervous activity is predominant in the follicular phase. A difference of the balance of ovarian hormones may be responsible for these changes of autonomic functions during the menstrual cycle. © FASEB.