Relative Weight and Race Influence Average Age at Menarche: Results From Two Nationally Representative Surveys of US Girls Studied 25 Years Apart

Abstract

These analyses from 2 nationally representative samples of US girls suggest a drop of about 2(1/2) months in the average age of menarche during the time period between 1963-1970 and 1988-1994. This was paralleled by a concurrent shift in the population distribution of body mass index z-score toward higher relative weights.