Doctors in the study also evaluated boys using the Tanner scale, a five-stage ranking system developed from a 40-year-old British study. While Tanner is the textbook benchmark, doctors increasingly consider it outmoded because it involved only 228 white boys in juvenile detention in London and evaluated them from photographs.
In the new study doctors also took note of pubic hair, but, said Dr. Bachrach, “pubic hair is very very misleading” because it is a later, less predictable indicator.
The study’s lead author, Marcia E. Herman-Giddens, a child and maternal health specialist at University of North Carolina Chapel Hill, said she originally proposed an additional measure used in Europe: identifying through urinalysis, or by asking, if boys had begun to ejaculate. But she said that urinalysis would have made the study more expensive, and colleagues reviewing the proposal “just freaked out” about the prospect of asking boys about ejaculation, wondering, “How would a child understand that?”
Dr. Herman-Giddens led a large study on girls’ puberty in 1997, and its conclusion that girls were developing earlier generated great controversy. Now, though, experts generally agree that subsequent research has shown breast development as young as 7 or 8. With menstruation, however, studies conflict: some suggest it is starting earlier, while others suggest the age has not changed much. Experts said this could mean that puberty is beginning sooner but lasting longer, or that different physiological processes underlie breast development and menstruation.
With girls, there is also scientific consensus that heavier girls enter puberty earlier, which makes sense, experts said, because body fat is tied to estrogen production.
In the study of boys, weight was not analyzed intensively, but the heaviest boys were developing earlier than what Dr. Herman-Giddens called “the little bitty skinny boys.” Experts said it is unclear if weight gain precipitates puberty or is a consequence.
Some experts said that while earlier development in girls can be worrisome because girls may be treated as more socially mature than they are, implications for boys are uncertain.
“With girls, the first signs are obvious, and social ramifications are much more pronounced and they’re negative,” said Dr. William P. Adelman, associate professor of pediatrics at the Uniformed Services University of the Health Sciences in Bethesda, Md., and a member of the Academy of Pedatrics committee on adolescents. But early-maturing boys “get called on more in school, tend to be better athletes. I’m less likely to get a parent of a boy saying, ‘Oh my gosh, my boy’s developing — he’s too young,’ ” Dr. Adelman said. More common is, “My boy, he’s a freshman in high school, his best friend is 6 feet already and he’s 4-11.”
Dr. Frank M. Biro, a puberty researcher and director of adolescent medicine at Cincinnati Children’s Hospital, said there are some common implications for girls and boys.
“If kids are looking older, it means that parents should be monitoring them, because that superego doesn’t kick in until late teens or early 20s,” he said. “The kids need a hand. Know what they’re doing.”
The New York Times, October 20, 2012)
