The timing of sexual maturation and secular trends of menarchial age in Korean adolescents

Abstract

Purpose : The purpose of this study was to evaluate the timing of sexual maturation and secular trends of menarchial age in Korean adolescents. Methods :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. Results :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. Conclusion : 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. (Korean J Pediatr 2006;49:610-616)