American boys appear to be maturing sexually at a younger age, a cross-sectional study showed.
Compared with studies going as far back as the 1930s, boys evaluated at well-child visits across the U.S. from 2005 to 2010 were growing pubic hair and achieving testicular enlargement 6 months to 2 years earlier, according to Marcia Herman-Giddens, PA, DrPH, of the University of North Carolina at Chapel Hill, and colleagues.
There were some differences depending on race/ethnicity, with blacks entering puberty earlier than whites or Hispanics, the researchers reported online in Pediatrics. The study was published to coincide with the American Academy of Pediatrics' annual meeting in New Orleans.
The observational design did not allow for an assessment of possible reasons for the results, although the authors pointed to chemical exposures and changes in diet, physical activity levels, and other lifestyle factors as potential explanations.
Recent studies have suggested that U.S. girls are entering puberty about a year earlier than they were 40 years ago, but less is known about the maturation of boys.