The duration of menstruation is calculated from the first day of menstruation until the first day of the next menstrual period, counting a complete menstrual cycle.
Under normal circumstances, menstrual cycles tend to last 21-35 days, with an average of 28 days. The number of days each period lasts, that is, from the time of menstruation to the end of menstruation, is usually 2-8 days, with an average of 4-6 days, and if it lasts for more than 8 days, it is called prolonged menstruation.
Menstruation is affected by a variety of factors, such as emotions, stress, medications, etc. Generally, menstruation is within the normal range of one week early or late.
In non-pubertal and perimenopausal women, menstrual cycles of less than 21 days are considered frequent. If the menstrual cycle is greater than 35 days, it is called scanty menstruation, which is an abnormal phenomenon, and prompt medical attention is recommended.