It is interesting to note the above mention of wiccan attitudes to mestruation. It is true that Judeo-Christian-Islamic attitudes to anything sexual or female are entirely negative and I think the whole 'menses are dirty and bad' thing comes from Leviticus and the passage about burning your bed if a woman has her monthly cycle in it. Probably based on fairly common sense 'survival in the desert without causing an epidemic' concepts, like the stuff about burning your tent if you have mildew, but still stuck to today in some form or another for all the wrong reasons.