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US boys now attaining puberty earlier

Robin Wulffson MD's picture
earlier puberty, boys, girls, endocrinology, hormones, testosterone, estrogen

According to a new study, boys in the United States are starting puberty six months to two years earlier than described in previous research. The study, conducted by the American Academy of Pediatrics (AAP), was published online on October 20 to coincide with the AAP National Conference & Exhibition in New Orleans. It is slated for publication in the November 2012 edition of the journal Pediatrics.

The study, termed “Secondary Sexual Characteristics in Boys: Data from the Pediatric Research in Office Settings Network,” notes that the trend toward earlier onset of puberty in girls has been supported by extensive research. The authors explain that, prior to this study, very little research has addressed the age of onset of puberty in boys in contemporary times.

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

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The researchers found that the observed average ages of stage the standard indicators of pubertal onset, stage 2 genital and pubic hair growth, and early testicular enlargement, were six months to two years earlier than documented by data several decades earlier. The 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. The researchers reported that, overall, African-American boys were more likely to start puberty earlier than white or Hispanic boys. They suggest that 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.

Study author Marcia E. Herman-Giddens, DrPH, noted, “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. 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 US boys,” added 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. 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.”

Take home message:
This significant finding bears further investigation. One theory for earlier puberty in girls is that it is driven by estrogen added to the diets of beef and poultry. However, if that is a factor, it would not influence or might delay puberty in boys.

Reference: American Academy of Pediatrics