[Lap] Dancers made about $70 an hour during their peak period of fertility, versus about $35 while menstruating and $50 in between.... from Psychology Today: The Stripper's Secret --Flaunting your fertility makes for big tips. The showgirl's guide to maximizing income by Matthew Hutson.
Now tell me there isn't a bucket load of sexism shining through the article, the title and the sub-title.
Really, the dancers are 'flaunting' their sex or zeroing in on the proclivities of the males of their species regardless of their fertility status. It just appears that that 'flaunting' is more successful when the body's reproductive objective lines up with the dancers' pecuniary objectives.