It was narrated from 'Aishah that Umm Habibah bint Jahsh who was married to 'Abdur-Rahman bin 'Awf suffered from Istihadah and did not become pure. Her situation was mentioned to the Messenger of Allah (ﷺ) and he said:
That is not menstruation, rather it is a kick in the womb, so let her work out the length of the menses that she used to have, and stop praying (for that period of time), then after that let her perform Ghusl for every for every prayer.