Firebreathing, Nauli and menstruation

Body: 

Can any one explain whyfirebreathing is not safe for menstruating women? Does the same restriction apply to naul

There is a chance these sorts of exercises could reverse the flow of menstrual fluid - causing it to back up into the tubes and out into the pelvic interior, leading to the disease of endometriosis. It is just a precaution.

on a practical note, precations aside, I find that it increases bleeding and cramping. (just because I was not responsible and tried firebreathing while menstruating does not mean I condone the practice, lol. do as I say....)