Boys in the United States may be entering puberty earlier than in generations past, suggesting that it is not just girls who are developing at younger ages, a study has found.
In comparison with decades-old data, boys who were examined during wellchild visits between 2005 and 2010 were found to be maturing six months to two years sooner, based on genital development.
The finding is important for parents, who have to know how and when to discuss changing bodies with their children, according to the lead author of the study that was published online by the journal Pediatrics last Saturday.
"They need to talk to their boys, earlier than they would have thought, about puberty and sexual development and all of those related issues," said Dr Marcia Herman-Giddens at the University of North Carolina at Chapel Hill.
Recent studies from the US and elsewhere showed that girls are maturing at a younger age, with many starting to develop breasts as early as age seven or eight.
Doctors have not thought that the same early puberty trend applied to boys.
Some doctors blame estrogen-like chemicals in the environment for girls' earlier development.
Those chemicals would be expected to delay sexual maturation in boys.
But, even if boys are developing earlier than in the past, it does not mean that they are more mature socially and psychologically at younger ages, researchers said.
Dr Frank Biro, head of adolescent medicine at Cincinnati Children's Medical Center, who was not involved in the analysis, said: "Now, there's a bigger disparity between (boys') physical maturation and their psycho-social maturation.
"People are going to interact with them like they're older."