Interpreting the Continued Decline in the Average Age at Menarche: Results from Two Nationally Representative Surveys of U.S. Girls Studied 10 Years Apart

Average age at menarche in the United States declined by 2.3 months between 1988-1994 and 1999-2002; by race/ethnicity, declines were considerably smaller. Changes in the population distribution of race/ethnicity and relative weight should be considered when interpreting trends in age at menarche.