The normal length of a woman’s menstrual cycle is 28 days, but this varies between individuals. Irregular menstruation is when the length of the cycle is more than 35 days, or if the duration varies. A menstrual cycle lasts around 28 days, but it can vary from 24 days to 35 days, depending on the individual. Most women have between 11 and 13 menstrual periods each year. Bleeding usually lasts around 5 days, but this too can vary, from 2 to 7 days. However, for some women, the time between periods and the amount of blood shed vary considerably. This is known as irregular menstruation. The main symptom of irregular menstruation is when the cycle is longer than 35 days, or if it varies in length.