All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.
It is permissible for a fasting person to take a bath in any given time during his fasting, and we are not aware of any evidence from the Book of Allaah or the Sunnah of the Prophet that prohibits it. Moreover, no scholar has ever issued a Fatwa that it is forbidden for a fasting person to take a bath, even though some scholars are of the view that it is disliked to do so. Nonetheless, the majority of the scholars are of the view that it is permissible for a fasting person to bathe whether it is an obligatory one (a ritual bath) or an optional one.
Similarly, it is permissible for a woman after the end of her menses to pray while wearing the clothes which she wore during her menses without washing them as long as they are not stained with the blooding of the menses. It is reported that Mujaahid said: 'A woman can perform the prayer in her garment which she wore during her menses unless it is stained with blood, in which case she should wash the blood stains.' [Ibn Abu Shaybah] Furthermore, Al-Hassan Al-Basri was asked whether a woman can perform the prayer while wearing the clothes she wore during her menses, and he replied: 'Yes, she can, unless she sees some stains of blood, in which case she should wash the place stained by it.'
Allaah Knows best.