Getty
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A recent study by American Academy of Pediatrics (AAP) has found 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 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 similar study by PROS was published in 1997 revealing that puberty in girls has been occurring earlier in contemporary times but until now, little research was available on the age in boys.

The 2012 study included 212 practitioners in 144 pediatric offices over 41 states, and information from over 4,100 boys was recorded. It found that the indicators of pubertal onset – stage 2 gential and pubic hair growth, and earlier testicular enlargement – were 6 months to two years earlier than documented in data decades earlier.

The earliest stage of puberty recorded occurred in non-Hispanic white boys at 10.14 years; in non-Hispanic African-American boys at 9.14 years and in Hispanic boys at age 10.4.

More research is needed to determine the reason for this shift to early onset puberty.

"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."