Some girls are only six or seven when they have to cope with their first period and a recent US study has found that boys are also hitting physical maturity up to two years earlier than in the past, The Sun reported.
Scientists have also found that the average age for the onset of puberty in girls in 1860 was 16.6 years.
By 1920 it was 14.6, in 1950, 13.1, in 1980, 12.5 and in 2010 it had dropped to 10.5.
Experts fear this could lead to an increase in young girls getting pregnant.
Puberty is the process of body changes from the first signs of adolescence to full adult development.
It is brought about by a series of chemical signals, which are sent from the brain to the pituitary gland in the head, then from the pituitary to the sex glands, the ovaries in girls and the testicles in boys.
These in turn make the sex hormones
