Trends in age at menarche from 1943 through 1989 in Taiwan: A retrospective population-based analysis.

Recent studies have demonstrated a global decline in the age at menarche. Our study aimed to determine the age at menarche of Taiwanese women born between 1943 and 1989. Data were obtained from the Taiwan Biobank. To view the trends in age at menarche, we analyzed data from 74,799 women. The mean, standard deviation, and annual percentage change in age at menarche were calculated for birth-year cohorts. The mean age at menarche of Taiwanese women born in 1943 was 14.85 years. The age at menarche decreased to 12.20 years for those born in 1989. The mean age at menarche declined by 2.65 years across the 47-year study period; hence, the reduction rate was 0.56 years per decade. This study demonstrated a downward secular trend in the age at menarche of Taiwanese women born between 1943 and 1989. This trend occurred in three stages of decline: fast (1943–1953), slow (1953–1965), and moderate (1965–1989). The age at menarche decreased by 2.65 years among Taiwanese women born in 1943 compared with those born in 1989. This decline occurred in three stages: fast (1943–1953), slow (1953–1965), and moderate (1965–1989). This significant downward secular trend in age at menarche reflects Taiwan's socioeconomic development. [ABSTRACT FROM AUTHOR]