Irregular menstruation refers to deviations from the usual menstrual pattern. This includes changes in the time between periods, the length of bleeding, or the volume of blood shed.
The primary reason is an imbalance between the oestrogen and progesterone hormones. Other factors can be stress, travel, a shift in contraceptive methods, unexpected pregnancy, or an early miscarriage. Menstrual cycles tend to be irregular during the initial years and for a few years leading up to menopause.