New study: Boys’ puberty starts at 9

A shirtless boy in puberty, with a crab instead of a penis

Boys are beginning puberty six months to two years earlier than in previous decades, mirroring a trend in girls, according to a new study by the American Academy of Pediatrics—though the reasons aren’t yet clear.

The study, the first large-scale look at puberty in U.S. boys in 25 years, found that on average boys now undergo the first signs between the ages of 9 and 10. That compares with average ages of 11 years or more in a number of previous studies examined by the researchers.

The trend was most pronounced in African-American boys, who start to develop the early signs of puberty, defined by genital enlargement, at 9.1 years. For Hispanic boys, the average is 10 years, and for white boys, 10.1 years, according to the study published online Saturday in the journal Pediatrics.

Graph of ages at what boys' puberty begins from 1970s until today

Similar trends toward earlier puberty in boys have been seen in smaller U.S. studies, and in studies in Europe and China.

Source: Wall Street Journal

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