What is the ruling on fasting, prayer, and marital intimacy when brown discharge occurs before menstruation, and is this discharge considered part of the menstrual period?

If the period following the last menstruation is less than fifteen days, then the blood is [due to] irregular bleeding (fasad), and it is obligatory to perform ablution for every prayer after the time for it has begun, and [it is permissible to] pray, fast, touch the Qur’an, and recite the Qur’an.

However, if more than fifteen days have passed since the last menstruation, then the blood is menstrual blood, regardless of its color. It invalidates the fast and necessitates making it up if it was obligatory, and prayer is not valid.

In this case, some scholars are of the opinion that one should refer to the distinction between menstrual blood and other blood, or else to the previous customary period. Others are of the opinion that one should refer to the customary period without considering the distinction.

Inserting an IUD is Islamically prohibited except in cases of dire necessity or extreme need, because it requires exposing the severe 'awrah, in addition to often causing a disturbance in the menstrual cycle, which affects the rulings of purity, prayer, fasting, and other matters.