Thanks for sharing! 
I just noticed when the subjects took PM: "2 weeks after menstruation finished for 7 days", which is the period when estrogen levels are declining. 88% of the subjects did not experience any change in the length of the menstrual cycle. So it looks like there is yet another time period to take PM, for those who want to minimise messing up their cycles!
I just noticed when the subjects took PM: "2 weeks after menstruation finished for 7 days", which is the period when estrogen levels are declining. 88% of the subjects did not experience any change in the length of the menstrual cycle. So it looks like there is yet another time period to take PM, for those who want to minimise messing up their cycles!