Is the incidence of precocious puberty increasing?

Updated: Nov 30, 2020
  • Author: Paul B Kaplowitz, MD, PhD; Chief Editor: Robert P Hoffman, MD  more...
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Answer

In 1999, as a result of the Herman-Giddens study, Kaplowitz and Oberfield published new guidelines recommending that puberty be considered precocious only when breast development or pubic hair appear before age 7 years in White girls and age 6 years in Black girls. [6]  However, most clinicians continue to use the 8-year definition.

In 2010, a study by Biro et al reported that in a cohort of 1239 girls aged 7-7.99 years from three urban centers, the proportion who had reached Tanner 2 breast development was 10.4% of White girls, 23.4% of Black girls, and 14.9% of Hispanic girls. [7]  While this was a cross-sectional study, the results confirmed that in the United States, the appearance of breast development prior to age 8 years is quite common. Follow-up of this cohort has indicated that none of these apparently early maturing girls were actually diagnosed with and treated for CPP (Biro F, personal communication, 2020). This suggests that the majority of girls who have breast development before age 8 years do not have the rapidly progressive form of CPP, which requires treatment.

Reliable estimates of the frequency of precocious puberty in boys have not been published. However, several centers have reported that they evaluate between one fifth and one tenth as many boys as girls for sexual precocity. Whether early puberty in boys is becoming more common over time, as is the case in girls, is unclear. However, a study from Denmark found that the mean age of testicular enlargement in boys declined from age 11.92 years to 11.66 years between 1991-1993 and 2006-2008, suggesting that more boys may be starting puberty before age 9 years. [8]


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