The evolution of the age at menarche from pre-historical to modern times

A significant retardation of the age at menarche occurred in the beginning of the modern times, soon after the industrial revolution, due to the deterioration of the living conditions, most studies reporting menarche to occur at 15–16 years. In the 20th century, especially in the second half of it, in the industrialized countries, the age at menarche decreased significantly, as a result of the improvement of the socioeconomic conditions, occurring between 12–13 years. In the present times, in the developed countries, this trend seems to slow down or level–off.
                                                              Journal of Pediatric and Adolescent Gynecology , 01/04/2016