It is narrated from Sayyidah Umm Salamah (may Allah be pleased with her) that Sayyidah Fatimah (may Allah be pleased with her) came to the Messenger of Allah (peace and blessings be upon him) and said: I keep seeing blood. So the Messenger of Allah (peace and blessings be upon him) ordered her to take a ritual bath (ghusl) and to perform ablution (wudu) for every prayer.
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 19881