Menarche

Menarche refers to a girl's first menstrual cycle, or first menstrual bleeding. The word menarche is derived from the Greek words me–n, month, and arche–, beginning. From both social and medical perspectives it is often considered the central event of female puberty, as it signals the possibility of fertility.

Timing of menarche is influenced by both genetic and environmental factors, especially nutritional status. It usually starts sometime between ages 11 and 14. But it can happen as early as age 9 or as late as 15. The average age of menarche is about 12 years. During the menarche period, menstruation may be irregular and unpredictable. Mood, weight, activity level, and growth rate may fluctuate with the hormone levels as well.