Menstruation (utusamaya) is a woman's monthly cycle of fertility and infertility. It is a natural process essential for reproduction. Many religions and cultures associate menstruation with impurity, bad luck or inauspiciousness. According to the Bible a woman is ritually impure during her menstruation and anyone or anything that touches her during that time likewise becomes unclean (Leviticus 15,19-23). Most Christians ignore these teachings nowadays although devote Jews still adhere to them. In Islam a menstruating woman is forbidden to do certain otherwise obligatory religious practices and sexual behaviour is strictly forbidden. The Manusmçti, Hinduism's most authoritative law book, says that a man must not have sex with his wife, accept food from her or even talk to her if she is menstruating.  Under Hindu law it was thought right for a girl to be married off shortly after her first menstruation. The Buddha considered this to be improper (Sn.110).

The Buddha rejected the idea of ritual purity and impurity and did not indorse any restrictions on menstruating women. His main concern was with what he called the  `inner washing'  (M.I,39), i.e. developing a mind  of love, kindness and honesty, and free from greed, hatred and delusion. Some Buddhist cultures have forgotten the Buddha's teaching on inner purity as opposed to ritual purity and continue to adhere to various menstruation superstitions. In some parts of Thailand women in this condition are not allowed to enter temples or circumambulate ståpas. In Burma they will not visit temples during this time and they are not allowed to approach certain holy Buddha images or enter simas.