For an overview of the results, see the following links:
For details about the study methods and results:
The authors acknowledge that their results should not be interpreted as being statistically representative of boys in the entire U.S. population. Still, their findings suggest that boys are experiencing a drop in the starting age of puberty, similar to girls.
Some quotes from the Pediatrics article:
pg 1065: "In conclusion, our data suggest that US boys are beginning genital and pubic hair growth earlier than several decades ago in concordance with recent reports on girls. These data are consistent with recent trends from other countries, such as Denmark, Sweden, Great Britain, Italy, and China."
pg 1065: "Current environmental factors, including exposure to chemicals, changes in diet, less physical activity, and other modern lifestyle changes and exposures may be related to this apparent rapid decrease in the age of onset of secondary sexual characteristics and may not reflect healthy conditions."
An interesting contrast in theories about what's causing the drop for boys vs. girls is that obese boys seemed to have later puberty, whereas for girls it is thought to be a risk factor for earlier puberty. Other considerations, such as environmental factors, are similar for boys and girls.
Note that this study addresses earlier puberty in boys, but is not about central precocious puberty, strictly defined.
For related posts, see:
