The journal Pediatrics issued a study in 2010 that surveyed 1,200 American girls. It found that 23 percent of African-Americans, 15 percent of Latinas and 10 percent of Caucasian girls began puberty at age 7. A 2012 study by Pediatrics found that puberty in boys started up to two years earlier than previously measured, particularly among African-Americans.

Three Causes of Early-Onset Puberty

Precocious puberty has no identifiable causes. However, there are several triggering factors that may contribute to its advent. These can include:

1)    A tumor on the brain or spinal cord;

2)    A birth defect like excessive fluid buildup;

3)    Development of McCune-Albright syndrome, a genetic disease that targets skin color and bones and generates hormonal issues.

Radiation treatments to the brain or spinal cord also may trigger puberty. There’s also the possibility of a condition known as congenital adrenal hyperplasia, which is over-production of hormones by the adrenal glands; or hypothyroidism, which is when the thyroid doesn’t produce the proper amount of hormones. Any of them could be the early-onset culprit.

In precocious puberty, the testosterone or estrogen in a child’s body can cause early puberty onset. This uncommon form of puberty starts when the Gn-RH hormone that typically triggers the start of normal puberty instead releases estrogen or testosterone into the body.