The mathematical averages of the developmental weeks during the period from the 14th until the 40th week for the body weight, body length, crown-rump length, chest circumference, abdomen circumference, bi-acromial breadth, and the lengths of the upper and lower extremities from 3328 cases of the Korean fetuses (1720 of the male and 1608 of the female)´ have been presented.
According to these averages the studies were extended over.. the developmental features during each of those weeks by the analysing the amount of the weekly´ increment with the weekly increment coefficient throughout the period. Moreover, the. observatory analysis was further extended over the relationships between the amounts of those developments and those of the -body lengths by the analysing indices of those items over the body length.´ From these observations the following conclusions have been drawn.
1) The average of the body weight of the 40th from the both sexes was 3279.0 gm, which is 88.72 times of that of 37.0 gm of 14th.
2) The averages of the body length from both sexes were 117.2 mm for the 14th and 521.4mm for the 40th. The average of the 40th was 4.45 times of that of the 14th week.
3) Of the crown-rump length the mathematical averages from both sexes were 82.0 mm for the 14th, and 361.4 mm for the 40th week, and about 4.41 times of the growth was calculated at the last week in comparison with that of the 14th of the prenatal weeks. The indices of above items to the body length were arranged within 68 to 70, and were slightly decreased by the time . until 24th, and thereafter the indices were stabilized until the end week of the fetal life.
4) The average of the chest circumference of the 40th from both sexes was 319.9 mm which is corresponded to 4.50 times of that of the 71.2 mm of the 14th. The indices over the body length were distributed between 58 to 61, were slightly decreased with the time by the 26th, thereafter the indices were gradually increased until the end week ´of the fetal life.
.5) The average of the abdomen circumference of the 40th from the both sexes was 293.4 mm, was corresponded to 4.81 times of 61.0 mm of the 14th. The indices over the body length were arranged within 49 to 55, and the values of the indices were gradually increased with the time from 14th until the end week of the fetal life.
6) The average of the bi-acromial breadth of the 40th from the both sexes was 129.4 mm, and is corresponded to 4.79 times of 27.0 main from the 14th. The indices over the body length were ranged between 23 to 24.5, were shown the tendency off slight increment by 23 rd, week, thereafter the indices were stabilized until the end of the fetal life.
7) The average of the length of the upper extremity for the 40 th from both sexes was 209.6 mm, was worth to 4.77 times of 43.9 mm of 14th. The indices over the body weight were ranged between 35 to 42, were slightly increased with the time by the 22 nd, thereafter those were stabilized until shortly before the end, and were decreased during few weeks of the fetal life.
8) The average of the length of the lower extremity from the both sexes of the 40th was 213.9 mm, was equivalent for 5.15 times of 41.6 mm of 14th. The indices over the body length were ranged between 36 to 41, were increased rapidly with the time by the 23 rd, thereafter the increment was minimized gradually until the end of the fetal life.
9) The velocity of the growth per week were decreased more or less abruptly with the time at the periods in the 18th, 24th and 32nd weeks as shown in the tables of` the weekly increment coefficient with the figures on the semilogarithmic scale.
10) None of the sexual difference was found in each of the above observations under the statistical support throughout the period.
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