Researchers have found that similar to girls, U.S boys have begun to enter puberty earlier than previously.
Marcia Herman-Giddens from the University of North Carolina's School of Public Health and her colleagues found that American boys of the current generation have begun entering puberty at an earlier stage that they used to previously. According to the study, boys now enter puberty six to two years earlier that boys actually used to.
Whether this is only the case with the new generation or if this was true for the past generation as well, Herman-Giddens is not sure because similar studies conducted in the past, usually dealt with the study of girls entering puberty. One reason why studies of boys entering puberty have not been conducted widely is because it is difficult to tell when a boy enters puberty.
"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."
The start of menstrual cycle and enlargement of breasts are two clear signs that a girl has entered puberty. However, for boys there are no such clean and visible symptoms. The enlargement of testes and development of sperm are two signs that show a boy has entered puberty but these are not visible symptoms.
"'Yikes, we don't want to ask about that!' " Herman-Giddens said with a laugh.
The research was conducted with 12 researchers across the country examining more than 4,100 boys aged 6 to 16. The process recorded information on the boys' genital size and pubic hair appearance. These records were categorized into four stages. Stage 1 was the pre-puberty stage, Stage 2 - onset of puberty, Stage 4 and 5 were stages of puberty and stage 5 was adult maturity.
The findings were then divided on the bases of race and it was found that African-American boys start hitting puberty first, at about 9 years old, while non-Hispanic white and Hispanic boys begin developing around 10-years-old.
"This should have an impact on the public health community," Herman-Giddens said. "That might be normal now," she said, "but that doesn't mean it's normal in the sense of what's healthy or what should be. The changes are too fast. Genetics take maybe hundreds, thousands of years. You have to look at something in the environment. That would include everything from (a lack of) exercise to junk food to TV to chemicals."
"It was an important study to do, and their methodology is improved over prior studies in that they based their assessment of puberty in boys on what I consider to be the gold standard: the size of the testicles," said Dr. Laura Bachrach, a professor of pediatric endocrinology at Stanford University.
