Puberty is the process of physical changes by which a child's body becomes an adult body capable of reproduction. It is initiated by hormone signals from the brain to the ovaries in females. Puberty is characterized by the development of breasts, followed by pubic hair and onset of menstruation. The average age of puberty is 10-13 years. Puberty is considered ‘precocious’ or too early if it occurs before the age of 8 years.
The first menstrual bleeding or menarche, typically occurs about two years after breast development. The average age of menarche in girls is 11-12 years. It is considered delayed if it does not occur by the age of 16 years. The time between menstrual periods (menses) is not always regular in the first few years after menarche. Ovulation which is necessary for fertility, may not accompany the earliest menses. In postmenarchal girls, about 80% of the cycles were anovulatory in the first year.