CHANGES IN THE MATERNAL ORGANISM 517 



d. Chlorides. — The first estimations of the chlorides of the 

 urine in pregnancy indicated no variation from the non- 

 pregnant level (WinckeP). Repeated investigations have been 

 carried out since the discovery that a retention of chlorides 

 may occur in nephritis and lead to oedema (Widal ^). 



Biancardi ^ stated that oedemas in pregnancy were sometimes 

 due to the same cause, and might be cured by decreasing the 

 chlorides of the food. Next Cramer * affirmed that aU cases of 

 hydrops graviditatis without albuminuria were due to a re- 

 tention of sodium chloride ; and Boni, whose careful investiga- 

 tions of the urine in pregnancy have already been referred to, 

 found that the chlorine excretion was decreased, and remained 

 low during the puerperium. Along with this there is a retention 

 of water to maintain osmotic balance. Normally 90 to 100 per 

 cent, of the water taken in is excreted in the urine, but the 

 percentage fell to 72 per cent, in a primipara, 53 per cent, in a 

 multipara, and 48 per cent, in a twin pregnancy (Siemens ^). Such 

 a retention did not occur in a woman who was later deKvered of 

 dead twins, 93 per cent, of the water being excreted in the urine. 



Birnbaum's ® results are not in agreement with the others. 

 He states that a retention of chlorides occurs only in the 

 nephritis of pregnancy, and not in normal pregnancy or in 

 hydrops without albuminuria. In the blood-serum the 

 chlorides were 0-1740 per cent., and 0-1775 per cent, in two cases, 

 and 0-1733 per cent, in a non-pregnant woman. 



G. Respiratory Exchange during Pregnancy 



Modifications in the respiratory exchange arise from the 

 alterations in the maternal organism, and from the requirements 



' Winokel, Studien Uber Stoffwechsel, &c., Rostock, 1865. 



' Widal, " La cure de dechloruration dans le mal de Bright," Arbh. Oener., 

 vol. cxciii., 1904. 



' Biancardi, "Sulla cura deolorurante nolle nefriti e nolle albuminurie 

 nel campo ostetrico," Ann. di Oat. e Ginec, 1905. 



■* Cramer, ' ' Chlornatrium-Entziehung bei Hydrops Graviditatis, '' Monats- 

 schriftf. Oeburtsh. u. Oynak., vol. xxiii. 



6 Siemens, "Metabolism during Pregnancy, Labour, and Puerperium," 

 Johns Hopkins Hosp. Sep., vol. xii., 1904. 



' Birnbaum, " Excretion of Chlorides during Pregnancy," Arch. f. Gynak., 

 vol. Ixxxiii., 1907. 



