The purpose of this study was to evaluate the timing of sexual maturation and secular trends of menarchial age in Korean adolescents.

Nine hundred eighty two school students and 119 university female students were included. Tanner's pubertal assessment method was applied using a self-assessment sheet with pictures for their developmental stages. A medical checkup database from 1,156,022 women was also used to analyze the age of menarche from the year 1900 to 1980.

Onset of puberty was at 11.3±1.3 years(y) in girls and 12.1±1.5 y in boys and total pubertal duration was 3.6 y in girls and 3.3 y in boys. Height at the onset of puberty was 146.1±7.9 cm in girls and 152.7±9.8 cm in boys. Weight at the onset of puberty was 39.3±6.9 kg in girls and 47.7±14.4 kg in boys. The mean age of menarche was 12.0±1.0 y and mean age at nocturnal emission was 12.3±1.8 y. By age ten, 3.0 percent of girls experienced menarche, which increased to 41.1 percent by age 12, and 98.0 percent by age over 15. By SMR 2 breast stage, 18.2 percent of girls experienced menarche, which increased to 66.1 percent and 91.7 percent by SMR stages 3 and 4, respectively. By SMR 2 pubic hair stage, 52.0 percent and by SMR 3, 93.8 percent of girls experienced menarche. While the menarchial age of women born around 1980 was 12.4±1.1 y, the menarchial age of women born around 1990 was 12.0±1.1 y. Age at menarche has been advanced approximately by 2 years between 1900 and 1980 birth cohorts.

There was a downward secular trend in pubertal timing. Age at menarche has been advanced by 2 years during the last 80 years. Further large scale, prospective studies, including inspection by specialists, are needed to provide reference data for pubertal timing in Korean adolescents.