Influences on the onset and tempo of puberty in human beings and implications for adolescent psychological development.

This article is part of a Special Issue "Puberty and Adolescence". Historical records reveal a secular trend toward earlier onset of puberty in both males and females, often attributed to improvements in nutrition and health status. The trend stabilized during the mid 20th century in many countries, but recent studies describe a recurrence of a decrease in age of pubertal onset. There appears to be an associated change in pubertal tempo in girls, such that girls who enter puberty earlier have a longer duration of puberty. Puberty is influenced by genetic factors but since these effects cannot change dramatically over the past century, environmental effects, including endocrine disrupting chemicals (EDCs), and perinatal conditions offer alternative etiologies. Observations that the secular trends in puberty in girls parallel the obesity epidemic provide another plausible explanation. Early puberty has implications for poor behavioral and psychosocial outcomes as well as health later in life. Irrespective of the underlying cause of the ongoing trend toward early puberty, experts in the field have debated whether these trends should lead clinicians to reconsider a lower age of normal puberty, or whether such a new definition will mask a pathologic etiology.