Is the menstruating woman required to check whether her period has ended before Fajr?
Question

If the end of my menses is approaching, am I obliged to wake up before Fajr prayer in order to find out whether my period has ended or not? Please note that it had not ended before ‘Isha’ prayer. Do I have to wake up before sunrise in order to find out whether my period has ended or not? Please note that my period had not ended before the time of Fajr prayer.
Praise be to Allah.If the end of a woman’s period is approaching, she does not have to wake up before Fajr to check whether her period has ended or not, because that comes under the heading of extra effort and hardship of which this ummah has been relieved. No report to that effect has been narrated from the earliest generations. Rather the woman should check before she goes to sleep, and at the times of the daily prayers, so she should check before the sun rises, and between Zuhr and ‘Asr, and so on.
Al-Bukhari (may Allah have mercy on him) said: Chapter on the beginning and end of menses … The daughter of Zayd ibn Thabit heard that women were calling for lamps in the depths of the night to see whether their menses had ended. She said: The women never used to do that, and she rebuked them. End quote.
This report was also narrated by Malik in al-Muwatta’.
Ibn ‘Abd al-Barr (may Allah have mercy on him) said: The daughter of Zayd ibn Thabit only rebuked the women for checking on their status when it was not the time for prayer and the time for prayer was not approaching because the depths of the night is not a time for obligatory prayer, and women are only required to check on their status for the purpose of praying, so that if their menses has ended, they can do ghusl, because they are obliged to pray.
End quote from Fath al-Bari by Ibn Rajab al-Hanbali (1/491).
Al-Khurashi (may Allah have mercy on him) said in Sharh Mukhtasar Khalil (1/207): She does not have to check whether her menses has ended before Fajr; rather she should check when going to sleep and in the morning. In other words, during her menses and afterwards, the menstruating woman does not have to check whether her menses has ended before Fajr. That is neither obligatory nor recommended; rather it is disliked (makruh). She should check when going to sleep and at the time of each of the daily prayers, but what is required is to allow enough time so that she can do ghusl and offer her obligatory prayer. End quote.
So if she realises after Fajr that her period has ended, but she is not sure whether it ended before or after Fajr, she should pray Fajr only, and does not have to pray Maghrib and ‘Isha’. If she fasts on that day, it is not valid, because there is no certainty that her period had ended before Fajr.
And Allah knows best.