A cross-sectional survey of more than 17,000 girls in the United
States showed that 2.4% of African American girls had breast
development by 5 years, 3.4% had pubic hair by 5 years,
15.4% had breast development at 7 years, and 17.7% had
pubic hair by 7 years. Among white girls, 1.5% had breast
development by 5 years, 0.4% had pubic hair by 5 years,
5% had breast development by 7 years, and 2.8% had
pubic hair by 7 years. Thus, African American girls who enter puberty
after their sixth birthday and white girls who enter puberty after
their seventh birthday in the absence of any predisposing disease
are now considered to be normal by many authorities, rather than
precocious. However, there is a dissenting view that still considers
8 years of age as the lower limits of onset of female puberty: for
maximum safety it appears best to use the 8-year guideline for girls
being evaluated by providers in general practice, and pediatric
endocrinologists can best determine which of those require in-depth
evaluation and perhaps treatment.5 Boys normally enter
puberty after 9 years of age.