Must a menstruating woman pray Fajr if she wakes up after Fajr and is unsure about the time her menstruation ended?

If a woman doubts [the onset of purity] during a period of purity, she should add it to the nearest probable time it could have occurred, because the default is the continuation of menstruation until certain purity is achieved. Therefore, the woman asking the question is not required to make up the Fajr prayer, and she should consider herself purified after the sun has risen.