Secular trend of menarcheal age in southern Chinese girls.

Abstract

Southern Chinese girls aged 11 years and 9 months to 12 years and 3 months in Hong Kong have a mean menarcheal age of 11.50 years (standard deviation of 0.47) using the recollection method. Highly significant differences are found when compared to the 12-year-old girls in Hong Kong studied in the past decades. Therefore, a secular trend of earlier menarcheal age is demonstrated.