The age at which girls are reaching puberty is steadily falling. In 1840, the average girl was 16.5 years when she attained menarche—the onset of menstruation. By 1920, the age had dropped to 14.6; by 1950, it was 13.1; in 1980, 12.5; and 12.43 in 2020. By 2022, the percentage of U.S. girls who reached menarche by age 10 had risen to 10 percent from 7 percent.
By 2010, the average girl reached puberty at the age of 10.5. Not only is the drop in puberty age seen across race/ethnicity groups in the United States, but according to a study in the Journal of Adolescent Health, the same trend toward early puberty has also been reported in England, Israel, China, India, Korea, Ghana, Mexico, and Thailand.
