Girls Are Developing Too Early, Aren't They? by Dennis M. Styne, M.D.
Note first line: A rumor is in the air – and often in the news –that girls are starting puberty at ever-younger ages.
"The National Center for Health Statistics reported in 1973 that the average age that girls began menstrual periods (menarche) was 12.8 years, about the same as in the 1950s. Compare that to the most recent study of over 17,000 apparently normal girls, done in 1997. The overall average stayed the same, with an average age of 12.9 years for Caucasian girls and 12.2 years for African-American girls. Thus, there is no evidence that menarche begins earlier now than 50 years ago."