NZ Herald 5 November 2013
Girls of all races are entering puberty earlier than ever before, and new research suggests that obesity may a contributing factor, particularly in white girls.
Early puberty has been linked to a number of medical conditions, including increased risk of breast and ovarian cancer, as well as high blood pressure and depression.
White girls on average began developing breasts at a median age of 9.7 years, about four months earlier than found in a separate study in 1997, said the report in the journal Pediatrics.
A higher body mass index, or ratio of height and weight, was “the strongest predictor” of early breast development across all races in the study.
African-American girls continued to develop at earlier ages than whites and Asians, as previous studies have also found, though no earlier than was observed in previous studies from the late 1980s and 1990s.
Research from Denmark published in 2009 showed that girls were experiencing breast development nearly a year earlier than those born 15 to 16 years before.
An accompanying editorial in Pediatrics by Marcia Herman-Giddens of the University of North Carolina at Chapel Hill said that the reasons for early puberty are complex and may not be fully understood for some time.