What is the ruling on the prayer and fasting of a woman whose menstrual cycle has stopped due to taking birth control pills for a legitimate reason, and is it permissible for her to pray without interruption?

It is permissible to use birth control methods when needed, with the husband's permission and under medical supervision. If the menstrual period ceases due to these pills, the woman is treated as pure (ṭāhirah), so she prays, fasts, and does everything that pure women do. This is because the prohibition of these acts is linked to the presence of menstrual blood; when the blood is gone, the prohibition is lifted. This is supported by the Prophet's (peace and blessings be upon him) saying to the woman suffering from irregular bleeding (mustaḥāḍah): "If it is menstrual blood, then it is black blood that is recognizable. If that is the case, then refrain from prayer. But if it is the other [type of blood], then perform ablution and pray." The ruling revolves around its underlying reason; whenever the harm is present, its ruling is established, and when it is not present, it is not established.