Menarche ( ; Greek: mēn "month" + arkhē "beginning") is the first menstrual cycle, or first menstrual bleeding, in female humans. From both social and medical perspectives, it is often considered the central event of female puberty, as it signals the possibility of fertility.
Girls experience menarche at different ages. The timing of menarche is influenced by female biology, as well as genetic and environmental factors, especially nutritional factors. The average age of menarche has declined over the last century, but the magnitude of the decline and the factors responsible remain subjects of contention. The worldwide average age of menarche is very difficult to estimate accurately, and it varies significantly by geographical region, race, ethnicity and other characteristics. Various estimates have placed it at 13. Some estimates suggest that the median age of menarche worldwide is 14, and that there is a later age of onset in Asian populations compared to the West. The average age of menarche is about 12.5 years in the United States, 12.72 in Canada, 12.9 in the UK and 13.06 ± 0.10 years in Iceland. A study of girls in Istanbul, Turkey, found the median age at menarche to be 12.74 years.
Douglas Harper's Etymology Dictionary
n. The onset of menstruation; the beginning of the menstrual period. A girl's first period.
n. the first occurrence of menstruation in a woman
Usage examples of "menarche".
Grief and menarche have made of Miss Unwin a most peculiar little creature, demented and conventional by turns.
Alfie had almost certainly plucked from her the fresh gardenia of her maidenhood, for his chieftaincy of the Minids gave him carnal access to almost every female who had attained menarche.