A handful of small studies had suggested that the age at which girls enter puberty had been declining dramatically. This led to an explosion in possible explanations, from environmentalists who blamed it on manmade chemicals to some feminists who blamed it on the glut of sexualized images that children are exposed to. But a new, larger study published in the British Medical Journal confirms what other larger studies have reported — there has been little or no change in he age at which girls experience their first period.
In the study, 1,000 British girls completed a questionnaire about their first period. The average age at which the girls reported having their first period was 12 years, 11 months. This represents an almost negligible decline of about 6 months from the average menarche age from the 1950s and 1960s.
The small change is likely due to the same reason that the age of girl’s first period declined by more than a year between the 19th and 20th centuries — an overall improvement in general nutrition.
Sources:
No change found in age of menarche. National Center for Policy Analysis, May 4, 2001.
Girls maturing slightly earlier. The BBC, May 3, 2001.