No one is sure what is causing the change
Physical Development in Girls: What to Expect During Puberty
Why are today's young girls getting their first periods at earlier
Were people less healthy back then? My grandma says most girls
IJERPH, Free Full-Text
They're Chasing Us Away from Sport”: Human Rights Violations in
Puberty Starts Earlier Than It Used To. No One Knows Why. - The New York Times
Why do people consider pre-teens 'little kids' when they have
Were people less healthy back then? My grandma says most girls
Onset of puberty in girls has fallen by five years since 1920, Children
Searching for Answers: Earlier Puberty Over the Last 200 Years – Montessori Muddle
Generation Z - Wikiwand
Why do people consider pre-teens 'little kids' when they have
Is it normal for my 16-year-old sister to still be watching TV
With puberty starting earlier than ever, doctors urge greater
