Many experts say that on average, puberty is starting earlier in the U.S. than it did in the past. The average age of menstruation has stayed roughly the same. But studies suggest that early signs -- like breast development -- are happening a year earlier than they did decades ago.

Why did I start puberty so early?

Most commonly, especially in girls, precocious puberty is due to the brain sending signals earlier than it should. There is no other underlying medical problem or trigger. This also can often run in families. Less often, precocious puberty stems from a more serious problem, such as a tumor or trauma.

Are boys entering puberty earlier?

It's not just girls, a study from the American Academy of Pediatrics found that boys were starting puberty earlier than previously recorded. According to the findings, boys are now beginning puberty around, or a little before age 10. Previously, 11 years of age was the given number where boys began puberty.