The onset and termination of menstruation is subject, like all other sexual phenomena, to
immense variation. It
has been known for a girl to start menstruating at three months old (H. Jolly in "Sexual
Precocity", Proc. Royal
Soc. Med. 44, 1951), and occasionally the menopause too occurs at a very early age:
there are instances of girls
reaching the menopause before the age of twenty. The menopause rarely occurs after the age
of fifty-five but rare
cases do occur. In one instance menstruation was continuing in a woman aged 104.