Secular Trends in Age at Pubertal Onset in Girls

Many studies focus on the onset of menarche as a marker of puberty instead of the first clinical sign of central puberty, thelarche. To examine secular changes worldwide in the age of pubertal onset using thelarche as a marker, researchers conducted a systematic review and meta-analysis of studies in healthy girls who presented for a clinical evaluation between 1977 and 2019.

Thirty studies representing most regions of the world were included in the meta-analysis. A statistically significant decrease of 0.24 years per decade was observed in age at onset of thelarche (Tanner breast stage 2). By region, the earliest pubertal onset occurred in the U.S. (median age, 8.8–10.3 years) and the latest in Africa (median age, 10.1–13.2 years).