age at onset of periods
The age at which first sign of initiation of puberty is noticed relates with the age at which the first period sets in. Tiny breast buds are the first external sexual character noticed around 10 yrs of age. About 6 to 12 months later sparse growth of pubic hair is seen. Interval between the first period and the appearance of breast buds is usually 24 to 30 mo, but can be as long as 6 years.On the other hand, 8 - 10 percent of normal girls get their first period even before 11 years of age.
The Expert, Ren Chats, Answers: Average age for the onset of menses is 12 years & 9 months to 13 years & 9 months. This is generally true for all ethnic groups and all geographical regions in the world.