FIELDS, GRAPHS, AND OTHER DATA ON FETAL GROWTH. 



By Arthur William Meyer. 



At the suggestion of Professor Mall and through the courtesy of Professor Williams I 

 was enabled to obtain abstracts giving the fetal measurements, the duration of pregnancy, 

 and such other data as might be desired from the case histories of patients from Professor 

 Williams' clinic. As these abstracts were made more than half a decade since, they do 

 not cover the entire material from the Department of Obstetrics of the Johns Hopkins 

 Medical School, but only 4,530 cases. The immediate object of making these abstracts 

 was the utilization of the data so obtained for the correction and, so far as might be, also 

 for the extension of the curve of prenatal growth for length. 



Since material from early abortions is comparatively rare among the cases ordinarily 

 coming for obstetrical care, by far the largest part of the statistics covered the later months 

 of pregnancy only. From the 4,530 abstracts, 2,470 were selected for the construction of 

 graphs of growth. For this purpose the cases were usually plotted with duration in days 

 as the abscissa and weight in grams or length in centimeters as the ordinate. However, on 

 one chart weight in grams was used as the abscissa and length in centimeters as the ordinate. 

 Other graphs were also formed to reveal the character and to illustrate the reliability of the 

 data themselves. All plotting was done on a large and corresponding scale and cases 

 falling at the same point of intersection were indicated by an Arabic numeral at that point. 

 Although only 2,476 different cases were involved, approximately 12,000 plottings were 

 done. The time-consuming nature of this work has been largely responsible for the delay 

 in the compilation and analysis of the abstracts, the taking of which was a rather arduous 

 task in spite of the careful way in which the histories are kept. 



As is shown by reference to the original charted fields here reproduced, the graphs are 

 medians and not averages. The most outlying cases were ignored, and those falling at 

 different distances from the median were assigned equal value in its determination. Hence, 

 all that these curves signify is that as many cases fall on the one side of the median as on 

 the other, but not that most of the cases lie on it nor that the cases falling on it represent 

 the average length or weight of the fetuses at that age. The empirical mode was not deter- 

 mined, except for birth, length, and for the occurrence of labor, as figures 5 and 6 show. 



Although some of the outlying cases show clearly that there is occasional error (unavoid- 

 able no doubt) in sonle of the histories, it was thought best not to make corrections, since 

 purely arbitrary criteria would have to be followed in making them. Besides, in so doing 

 there is danger of eliminating all cases representing wide but entirely normal fluctuations. 

 In the selection of the histories cases were included or excluded for plotting solely on the 

 basis of the character of the histories themselves — sometimes the whole history — but only 

 rarely, on account of the character of individual measurements, unless these had been 

 called in question by those taking them or were brought in question by the subsequent 

 history of the case to which they belonged. 



Before proceeding to a discussion of the graphs a summary of the cases utilized will be 

 given. This will convey a better idea of the character of the data used for graphical 

 representation. The publication of the original charts as plotted also enables anyone to 

 draw his own curves and conclusions and reveals any personal equation that may have 

 intruded itself. 



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