For females, the age of the bones at menarche ranges from 11 to 16 years, with the majority being 13 to 14 years.
It is now believed that there is a close relationship between the degree of calcification of the bones and the time of the first menstruation. For women in general, the bone age at the time of menarche is 11~16 years old, and most of them are 13~14 years old. However, the menarche is affected by nutritional intake, medication, family genetics and other factors and there are large individual differences.
With the improvement of people’s material life, there are some well-developed, well-nourished women, the age of menarche is also earlier than before, can be found in the age of 9 ~ 10 years of age on the first menstruation, at this time there is a phenomenon that the bone age is greater than the age of the phenomenon, these girls are generally taller than their peers, enter puberty earlier, breast development and other secondary sexual characteristics also appear earlier.