Women's first menstruation age has not always remained the same. Among us in 1840 the average age was 16.5 years and currently 12.8 years. However, according to one study, in many industrialized countries this age tends to increase.
It must be said that thanks to the advance in our society, especially in hygiene and food, the age of three or four months has been reduced in every decade. This age depends on the length and weight of the girl. In the United States, for example, the average weight is 47.8 kilos and the length is 1, 58 meters.
The importance of weight at that age is known. Adipose tissues are the main source of estrogen and metabolism has been governed by the estrogen rate. In obese girls an ineffective form of estrogen is created.
In recent years, however, the age of the first month is lagging in industrialized countries, although hygiene does not recede. However, food and lifestyle have changed. Young girls care much more about their "shape" and thinness and get more hours into sports. As a result, adipose tissue reserves decrease.
That is not a medical concern. And it is that those who have the first menstruation quickly have more risk of breast cancer.