On Growth in Japanese Adolecent Girls

Abstract

The author in this study considered the relation between growth and puberty, based mainly on statistics concerning school girls in Niigata Prefec-ture.Thefollowing is a summary of the results which have been supple-mented by several other reports.(1)Observing the group as whole, the period of female puberty is from eleven to seventeen or from twelve to sixteen years, being one or two years earlier than in males.During this period the relative physical yearly growth-rate successively decreases(table 1 in stature, table 3 in width of mammal part).In this period, in the case of almost every girl, the hair of the armpit begins to develop(table2, left)and the first menstruation is experienced (table 2, right).When the age-difference of puberty between both sexes was reduced so as to correspond, the sex-ratio of stature (93%) is almost changeless during this period, while those of measures like acromial width and hip-circum-ference gradually change to develop the sexual difference in body structure.(2) The period of puberty appears individually earlier or later almost according to the time of first menstruation, and at this time the relative physical growth-rate has already begun to decrease.(3) The mean age of first menstruation in the author's material is approxi-mately fourteen years. The frequency of individuals who experienced the first menstruation, is the highest in August for precocious sub-group (fig. 1, upper, straight line), and in April for the later-maturing sub-group (fig. 1, lower, straight line). Such a relation similarly has been found by MATSUYAMA ('44) between groups of precocious school girls and later-maturing labourers (fig. 1, dotted line).(4) At the first menstruation, the stature of Japanese girls is about 148cm independently of their actual age. Not only in stature but in other physical measurements, the same definite growth state seems to be found.