Prior to knowing more about the cause of irregular periods, it is necessary to understand what an irregular period is. Bear in mind that all females have different cycles with regards to menstrual period. For some, the cycle takes 28 days while it may take as much as 35 days for the rest. A number of women may also encounter light flow or spotting while others experience heavy menstrual flow. A normal period may last for 3 to 7 days. Irregular periods, nonetheless, are described as missed period or late cycles. Moreover, women experiencing abnormally heavy flow or having 2 periods per cycle are also encountering irregular monthly period.