The age of breast development — which represents the first clinical sign of female puberty — has declined an average three months per decade between 1977 and 2013, according to analysis of data combined from 30 different studies.
…
Puberty in Girls Starting Earlier and Earlier
The age of breast development — which represents the first clinical sign of female puberty — has declined an average three months per decade between 1977 and 2013, according to analysis of data combined from 30 different studies.
…