What is the ruling on a woman praying in her underwear due to non-menstrual female discharges?

A woman's undergarment is pure, and prayer is valid with it unless it is certainly known to have been soiled by secretions. If it has been soiled by secretions, then what exits from the urinary opening is impure and renders what it touches impure, whereas what exits from the birth canal is pure. If a woman prays with an undergarment that has been soiled by impurity, knowing and intending it, her prayer is invalid and must be repeated. However, if she was ignorant or forgetful, her prayer is valid.