NEW ORLEANS -- A study conducted by the American Academy of Pediatrics (AAP) has documented that boys in the U.S. are experiencing the onset of puberty six months to two years earlier than reported in previous research.

The study, "Secondary Sexual Characteristics in Boys: Data from the Pediatric Research in Office Settings Network," will be published in the November 2012 Pediatrics and published online Oct. 20 to coincide with the AAP National Conference & Exhibition in New Orleans. The trend toward earlier onset of puberty in girls is now generally accepted and supported by extensive research. Until now, little research was available on the age of onset of puberty in boys in contemporary times.

The study was designed and conducted through the AAP Pediatric Research in Office Settings (PROS) practice-based research network, a system of hundreds of pediatricians nationwide who contribute data to AAP-led scientific studies on children's health. A 1997 PROS study was the first large study to document earlier pubertal onset in US girls. For the study of pubertal characteristics in boys, 212 practitioners in 144 pediatric offices in 41 states recorded information on more than 4,100 boys.

This new research found that the observed mean ages of stage 2 genital and pubic hair growth, and early testicular enlargement - standard indications of pubertal onset - were six months to two years earlier than documented by data several decades earlier. Pediatricians recorded the earliest stage of puberty as occurring in non-Hispanic white boys at age 10.14 years; in non-Hispanic African-American boy at age 9.14 years, and in Hispanic boys at age 10.4.

Overall, African-American boys were more likely to start puberty earlier than white or Hispanic boys. Study authors say the causes and public health implications of an apparent shift toward a lower age of puberty onset for boys is unclear and warrants further research.

"Contemporary data on the ages of pubertal characteristics in U.S. boys from onset to maturity, lacking until now, are needed by pediatricians, public health scientists, and parents," said study author Marcia E. Herman-Giddens, DrPH. "Following changes in growth and development is an important part of assessing the health of the nation's children. I am grateful to the pediatricians and the boys who participated in this exciting study."

"All parents need to know whether their sons are maturing within the contemporary age range, but, until now, this has not been known for U.S. boys," said PROS Director Richard C. Wasserman, MD, MPH, FAAP. "The PROS study provides 21st century standards."

"The landmark PROS study of the 1990s provided contemporary data for girls' puberty," Dr. Wasserman said. "A study on boys puberty was a logical follow-up. Our pediatric endocrinologist colleagues now use the PROS puberty assessment training materials in their own studies and fellowship training."

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The American Academy of Pediatrics is an organization of 60,000 primary care pediatricians, pediatric medical subspecialists and pediatric surgical specialists dedicated to the health, safety and well-being of infants, children, adolescents and young adults. For more information, visit www.aap.org.