Studies on the physical Growth of Japanese Girls.

Report 1. First Menstruation and physical Growth.

Abstract

The author, Dr. Matsubayashi, studied the influences of the first menstruation on the physical growth of girls numbering 788 who were stndents of the Hiroshima girls' High School. His studies extended four years from March, the fifteenth year of Taisho (1926) to March, the fifth year of showa (1930), during which measurements of the height and weight of the body were taken every month. Dealing statistically with the relation between those findings and full years of age in the first menstruation, the author arrived at the lollowing conclusions; -
1. If full years of age in the first menstruation are separated every half a year and the distributions of those divided ages are observed, most cases of the first menses occur in the second half of thirteen years of age and in the first half of fourteen years, their percentage to the whole girls being 44%. Girls who had the first menstruous dischaige in 13 and 14 years of age are put at 72% of the whole. And the whole girls' averae age in the time of the first menses is of full fourteen years.
2. If the seasons of the first menstruation are brought to the object of observation, girls menstruating first in April are most numerous, ones in August and January next in order hnd others in November the least.
3. As for the process proceding to a regular periodicity after the first menstruation, 30% of the whole number, become regularly menstruous after the first occurrence and 37% in the lapse between two and six months, that is, most normals become regular within half a year. Those who come into regularity in the lapse between seven months and a year are 16% and others after. a year 16% too.
4. Girls who had the first menstruous discharge when they were in elementary schools are numbered 42(6% of the whole students) and those who had after they had graduated from the girls' high school are 13 (1.7%). In the average age These two groups differ only by about half a year. But the physical growth which they developed after they entered to the girls' high school was greatly differentiated;- the former group entering to the girls' high school with 147.2cm. in average height grew 5.3cm. during their four years' high school life, whereas the height of the latter commencing with 134.3cm. showed the increace of 14.9cm. during four years. As regards the average weight of the body, the measuring recordsr of the former group begun with 41.9kg., the increase for the period of fiou years being 9.1kg., and the average weight of the latter was 29.6kg. at the entrance to the high school, with the increase of 13.4kg. during four years. In other words, the former grew from 288 to 335 and the latter from 217 to 288 n the average body weight per centimetre.
5. Gills who had first had a monthly sickness in the early part of their highschool life grew slowly for the period, while ones who had in the later part grew rapidly. And the amount of growth of these both extremes shows a difference of 13cm.
6. The average stature measured in the month of the first menstruous discharge which 729 students had for the first time while in school is 148cm., almost alike without distinction of age.
7. Generally the increase of stature is always great before the first menses and small after that. But if viewed more accurately, it is known that the bodily growth of girls having the first discharge in an earlier time is a little greater than that of ones of a later discharge.
8. The suspension of stature development always occurs since the first menstruation was discharged, but in this case, the length of period lying between both phenomena is longer in late maturing girls and shorter in the precosity.