Menstrual bleeding that does not conform to a regular pattern. A natural process like menstruation will not always occur precisely every 28 days; a cycle which varies between 24 and 34 days is still considered regular. Irregular and often heavy menstruation frequently occurs in young girls, because the ovaries are not mature enough to produce adequate hormones to ensure a genuine menstrual cycle. These symptoms disappear in time. The cycle often becomes irregular towards the end of the reproductive period (menopause) as the ovaries are gradually losing their function. The cycle can seem irregular if a little bleeding occurs at the time of ovulation. Irregular menstruation can be caused in various ways. The reason is often disturbed hormonal balance or a disorder of the ovaries. Blood and urine hormone tests can be carried out, a curettage made and the ovaries examined by sonography.