Secular changes in puberty

Throughout the last century, several studies from the US and Europe have demonstrated a secular trend towards earlier pubertal onset, particularly in girls. The initial clinical sign of pubertal onset is breast gland development in girls and testicular enlargement over 3 mL combined with penile growth in boys. In girls, menarche is sometimes used as a late marker of puberty. The precise mechanism behind the onset of puberty and the secular trends of puberty remain to be elucidated. This article briefly describes the physiology of normal puberty and sexual maturation, historic and recent secular changes in age at pubertal onset in girls and boys as well as changes in the incidence of precocious puberty. The article also discusses the possible mechanisms explaining the recent advancement in the onset of puberty.