This, however, is unscientific. The natural process of shedding the uterine wall in actual fact helps to prevent uterine cancer. Post-menopausal women were given the female hormone progesterone to induce artificial menstruation to prevent the build up of cancer causing the endometrial layer. In Leviticus 18:19, God commanded the Israelites not to have sexual intercourse during a women's period for the reason of ceremonial cleanliness, not because it is an illness.