Polymenorrhoea is the term used to describe frequent periods. Classically it describes women who have a period more frequently than every 21 days.

The most common causes are related to menstrual cycles where no egg is produced (anovulatory cycles). This can occur in the climacteric (period leading to the menopause) and in women with polycystic ovaries. When no cause is found, this and other menstrual symptoms form part of the condition known as dysfunctional uterine bleeding.