Boys in the United States appear to be entering puberty much earlier than in the past – a trend researchers caution may have important medical, psychosocial, public health and environmental implications, according to a new study.
The research, published online in the journal Pediatrics, was presented Oct. 20 at an American Academy of Pediatrics (AAP) conference and exhibition in New Orleans.
“Pubertal data are an important part of monitoring the health of our nation’s children,” said Dr. Marcia Herman-Giddens, lead investigator for the study and adjunct professor of maternal and child health at the University of North Carolina at Chapel Hill’s Gillings School of Global Public Health. “Our findings suggest we need to reevaluate anticipatory guidance provided to boys – the famous ‘birds and bees’ talk may need to happen earlier – and examine what contributing factors might be behind this phenomenon.”
On average, boys now begin puberty at around ages 9 or 10, depending on race or ethnicity – a full six months to two years earlier than ages documented by data several decades ago. Researchers assessed pubertal onset through visual inspection of genitalia and pubic hair growth and physical measurement of boys’ testes – tell-tale signs that sexual development has started. Unlike in prior studies, researchers included the latter measure – testicular enlargement – a key physical marker of puberty.
Overall, African-American boys were more likely to enter puberty earlier than white or Hispanic boys. The earliest stage of puberty was found to occur at 9.14, 10.14 and 10.4 years in African-American, non-Hispanic whites and Hispanic boys, respectively. Researchers say they don’t know why these racial and ethnic differences exist.
“It may be largely genetic, as it is well known that different races have different timing in puberty, other factors being equal. But the variation also may be influenced by environmental factors,” Herman-Giddens said. “One thing that concerns me about our overall findings is the expanding gap between the onset of physical development in boys and the maturity of the brain.”
She said these two maturation processes rarely stay in sync, and early physical maturation only extends the period during which only one area of the person has developed. It’s not until late adolescence or early 20s before individuals develop mature judgment and cognitive abilities.
“Based on our study, boys are undergoing sexual development at an earlier age – earlier than in previous generations – yet, they are in no way equipped to deal with the issues that come with it,” Herman-Giddens said.
The study results underscore the need for parents, medical providers, public health officials, environmental researchers, school personnel and others to recognize the apparent shift to earlier puberty and how that may impact health, she said. In particular, clinicians may consider the findings when making decisions about further evaluation or referral of boys for apparent early or late onset of development.
Researchers studied secondary sexual characteristics in 4,131 boys at well-child visits in 144 pediatric offices in 41 states between 2005 and 2010. Boys ranged in age from six to 16 years. Boys with chronic conditions or medications that could affect puberty were excluded from the study.
