August 19, 2009
By Kathleen O’Grady
Writer; Research Associate, Simone de Beauvoir Institute, Concordia University; Principal of QUOI media group.
Most endocrinologists in North America agree that girls begin to menstruate at a younger age than in decades past. What is not as clear – and the subject of much debate – is why this is happening, and what – if anything – needs to be done about it.
Over the last 100 years, the average age of first menstruation for young white girls in the U.S. has declined from 17 to 13 years old, a drop that has significantly slowed over the last 50 years.
There is also wide ethnic disparity. White girls in the U.S. now menstruate at the average age of 12.6 years, black girls at 12.1 years, and Mexican American girls at 12.2 years. Small cohort studies indicate that Canadian data are comparable.