There you have it! A mechanism of interaction. Look at this chart in Wikipedia. You can see that for a new cycle to begin, estrogen has to go down (end of the cycle. My interpretation of the possible mechanism then is that, after the body causes an initial increase of estrogen, electrostimulation through hGH brings it down much more quickly, thus shortening the cycle. As a corollary, if you are trying to get pregnant I would stop electrostimulation for a couple of cycles to let it come back to regular.
Could you please tell me what acceleration you noticed? Days?