CHANGES DURING PREGNANCY 531 



pregnancy were made by Sillevis x on three primiparte and refer to 

 the twenty-eighth week, the thirty-fourth week, and the thirty- 

 eighth week of pregnancy. In every case he found a nitrogen 

 retention which amounted to an average of 2 gin. per diem. 

 The work of Bar 2 contains observations on ten women during 

 the end of pregnancy. Of these, nine showed a nitrogen retention 

 which varied from 2'26 to 7*50 gm. per diem in different individuals. 

 The tenth woman suffered from intestinal disturbances during 

 which she suffered a nitrogen loss. Some of the subjects of his 

 observations were examined later when not pregnant and showed 

 on the same diet a much smaller retention of nitrogen. 



The amount of nitrogen which is used by the foetus and the 

 genital organs is calculated by Bar to be 1'5 gm. per diem, so that a 

 normal pregnant woman on an adequate diet retains more nitrogen than 

 is required by the foetus with adnexa, the uterus and the mammary 

 gland. The mother adds, therefore, to her own store of nitrogen. 

 For this reason Bar describes the condition of pregnancy as " une 

 symbiose harrnonique homogene : 1'organisme maternel fournissant au 

 foetus le moyen de se developper, et cela aux^seuls depens de ce qui 

 dans la ration deviendrait matiere excrementitielle, sans rien perdre 

 par consequent. Par suite de 1'adaptation de sa nutrition aux 

 exigences nouvelles, la mere loin d'etre lesee semble souvent utiliser 

 pour elle-meme une partie de ralbumine, qui lui apporte une ration, 

 faite d'instinct plus abondante et mieux utilisee dans 1'intestin." 



The most prolonged investigation on the human subject is that of 

 Hoffstrom 3 who kept a primipara under continuous observation from 

 the sixteenth week on till the end of pregnancy. With a varied diet 

 he obtained the comparatively low nitrogen intake of 13 gm. per diem 

 on the average, with daily variations of a minimum of 10 gm. and a 

 maximum of 16 gm. On this diet lie obtained throughout the whole 

 period of observation a nitrogen retention of an average of 1*84 gm. 

 per diem, or fourteen per cent, of the nitrogen intake. The total 

 amount retained was 310 gm. N, of which 101 gm. were deviated to 

 the developing ovum. The maternal organism completed, therefore, 

 the pregnancy with the remarkable net gain of 209 gm. nitrogen. 

 It is equally remarkable that the body weight of the mother only 

 increased by 550 gm. Very similar results were obtained by 

 Landsberg 4 on several women. It must, therefore, be accepted as a 



1 Sillevis, "Jets over de Stofwisseling cler Gravida," Akad. Porfsckrift. 

 Leyden, 1903. Abstracted in J/ow.. /. (jfcbut-ts/iiilfe, p. 240, 1905 ; quoted 

 from Bar. 



2 Bar, loc. cit. 



3 Hoffstrom, loc. cit. 



4 Landsberg, " Untersuchungen liber den Stotfwechsel bei Schwangeren," 

 Zeitsch. f. Geburtsh. u. Gynaekol., vol. Ixxi., 1912. 



