Age of puberty in a representative sample of Iranian girls.

BACKGROUND To obtain normal references for growth and pubertal development in a given population, assessment of pubertal stages is of great importance. This study aimed to determine the age of appearance of secondary sexual characteristics in a representative sample of Iranian girls. METHODS This cross-sectional study was conducted during 2005-2006 in 3192 girl students, aged 6-17 years, in Isfahan, Iran. Participants were selected by multistage random cluster sampling from school students. Secondary sexual characteristics were evaluated by inspection and palpation, and were recorded according to Tanner staging. The self-reported date of menarche (if any) was recorded as well. Data were analyzed with Probit analysis based on the status quo method. RESULTS The median ages (10th-90th percentile) of Tanner stage 2 breast development (B2) and Tanner stage 2 pubic hair growth (PH2) were 10.14 years (8.33-11.95 years) and 10.78 years (9.09-12.48 years), respectively. The ages of the 3rd percentile for B2 and PH2 were 7.48 and 8.29 years, respectively. The median age of menarche among the 3192 girls who had experienced menarche was 12.65 years (11.18-14.11 years). CONCLUSIONS The median age of puberty onset is 10.14 years, and the onset of puberty before 7.5 years is considered as precocious puberty in a representative sample of Iranian girls. The values obtained from the present study can provide baseline data for analysis of time trends, as well as for international comparisons.