What is the ruling on spotting that begins before the menstrual period?

For a woman with a regular menstrual cycle, spotting that occurs before the start of her period is considered menstrual blood, and she is regarded as menstruating from that moment until the end of her usual period. Therefore, during the days when spotting occurs, she does not perform prayers or fast. However, if the bleeding continues for more than ten days, any bleeding after her usual period is not considered menstruation but is classified as irregular (excusable) bleeding. A woman whose bleeding lasts more than ten days should perform ablution and pray as those with a chronic excuse do. (Mevsılî, el-İhtiyâr, 1/30)

This is the general ruling found in fiqh sources. However, it is known that spotting before the menstrual period may result from premenstrual hormonal changes, and if a doctor determines that this is not menstrual blood, then for women with fixed menstrual days, any spotting before or after those days is considered excusable bleeding.

Source: T.C. Diyanet İşleri Başkanlığı, Din İşleri Yüksek Kurulu