What causes precocious puberty?

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

The timing of puberty has a genetic component. A history of early puberty in a parent or sibling is relevant and decreases the likelihood that early puberty has an organic cause. A study from Israel estimated that precocious puberty was familial in one fourth of cases and that the predominant mode of inheritance was autosomal dominant. [28]

An increased body mass index (BMI) has been strongly associated with earlier onset of thelarche and menarche, [29]  with, in some studies, the association being stronger in White females than in Black ones. However, the relationship between body fat and puberty is complex and has many exceptions, and although body weight and fat mass are clearly among the factors that may influence puberty onset in girls, obesity is not definitely associated with early puberty in boys, with only some studies showing a relationship.

A longitudinal study of 354 girls by Lee et al found that increased BMI at age 3 years and the rate of increase in BMI from age 3-6 years were both positively associated with an earlier onset of puberty. [30]  In addition, a meta-analysis of two datasets from adolescent girls in 34 countries in Europe and North America revealed an inverse association between age at menarche and individual BMI. [31]


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