Physiology, Menarche

Menarche is defined as the first menstrual period in a female adolescent. Menarche typically occurs between the ages of 10 and 16, with the average age of onset being 12.4 years. The determinants of menarcheal age are continuously being researched; socioeconomic conditions, genetics, general health, nutritional status, exercise, seasonality, and family size are thought to play a role.

Menarche tends to be painless and occurs without warning. The first cycles are usually anovulatory with varied lengths and flow. Menarche signals the beginning of reproductive abilities and is closely associated with the ongoing development of secondary sexual characteristics.