Dangerous to pose upside down while menstruating? A friend of mine studied under a very strict and traditionalist teacher and now teaches yoga herself. She tells me that it’s bad for a woman to do things like handstands or headstands while menstruating — pretty much any pose that puts the body in an upside-down position. Is this true? It seems like nonsense to me but I’d love to learn if there is anything behind it, either traditionally or medically.