Boys Starting Puberty Earlier, Like Girls

Boys in the United States are reaching puberty some 6 months to 2 years earlier than a few decades ago, reflecting the trend in girls, according to a new study by the American Academy of Pediatrics (AAP) published online before print on Saturday. The study authors suggest more research should now be done to find out why this is happening.

Lots of published evidence shows girls are reaching puberty earlier, and this is now generally accepted, but until now, there hasn't been as much research on whether today's boys are also showing a similar tendency.

AAP researchers designed and carried out the study through hundreds of pediatricians all over the US who belong to the AAP Pediatric Research in Office Settings (PROS) network and contribute data for research on children's health.

Data from this same PROS network was used in a large study that in 1997 showed US girls were reaching puberty earlier.

Parents and Doctors Need to Know

The data for this latest study covers more than 4,100 boys, and was recorded by 212 pediatricians carrying out well-child care in 144 practices in 41 states.

American boys appear to be reaching puberty at a younger age, with African-American boys entering puberty earlier than white or Hispanic boys.

Co-author Richard C. Wasserman, director of PROS, says:

"All parents need to know whether their sons are maturing within the contemporary age range, but, until now, this has not been known for US boys."

To assess puberty in boys, pediatricians measured two features: genital and pubic hair, and testicular enlargement, both standard indicators of start of puberty.

The results showed that puberty onset was happening some 6 months to two years earlier than it was several decades ago, according to records from that time.

Ethnic Differences

Overall, African-American boys are more likely to enter puberty earlier than white or Hispanic boys.

Across three ethnic groups, pediatricians recorded the earliest stage of puberty as 10.14 years in non-Hispanic white boys, 9.14 years in non-Hispanic African American boys and 10.4 years in Hispanic boys.

The authors write:

"The causes and public health implications of this apparent shift in US boys to a lower age of onset for the development of secondary sexual characteristics in US boys needs further exploration."

21st Century Standards

In a press statement, lead author Marcia E. Herman-Giddens thanks the doctors and boys who provided much needed data for "this exciting study":

"Contemporary data on the ages of pubertal characteristics in US boys from onset to maturity, lacking until now, are needed by pediatricians, public health scientists, and parents," she explains.

Wasserman says the landmark PROS study that was done in the 1990s provided up to date information on puberty in girls: it was logical there should be a similar one for boys:

"The PROS study provides 21st century standards," says Wasserman.

"Our pediatric endocrinologist colleagues now use the PROS puberty assessment training materials in their own studies and fellowship training," he adds.