Age at menarche in a group of French schoolgirls

Background Mean age at menarche in France decreased from 12.78 years in 1979 to 12.6 years in 1994. The aim of this study was to determine mean age at first menstruation in French adolescent girls in order to study the secular trend. Methods Age at first menstruation was noted to the nearest month during recording of anthropometric measurements in three secondary schools in the Aisne administrative department, France, in classes in years 7, 8, 9 and 10. A total of 339 girls aged 11–15½ years were examined. The majority were from a social background of workers, employees and middle managerial staff. Mean age at first menses and standard deviation were calculated using the probits method. Results Mean age was 12.5 ± 0.08 years (χ2γ=14 = 16.7, P > 0.05), indicating that it had remained stable for more than 15 years. Conclusions A secular decline has already been observed in Belgium, Britain, Hungary, Scandinavia and the USA. In all these countries, age at menarche has reached a stable level at around 13 ± 0.5 years.