FACTORS ALTERING CONCENTRATION OF BLOOD LIPIDS 407 



pregnancy. After delivery, the concentration of cholesterol and, in fact, of 

 all blood lipids, gradually returns to normal. 304 - 309 The rate of decline is to 

 some extent dependent upon whether or not the mother nurses her infant. 309 

 Peters and associates 310 confirmed the progressive rise of total and free 

 cholesterol, phospholipids, and neutral fat from the twelfth week of preg- 

 nancy to delivery, after which the value returned to normal. Neutral fat 

 was found to increase proportionally far more before delivery and to de- 

 cline more rapidly after parturition than did the other lipid fractions. 



Little information is available as to the changes in blood lipids in the 

 lower animals during pregnancy. Blood fat has been reported to increase 

 as term approaches, in the guinea pig, following fat feeding, 311 while a high 

 liver fat has been noted in pregnant rabbits. 312 However, Kaufmann and 

 Erdmann 313 detected no increase in blood cholesterol in pregnant rats, 

 although increased amounts of this sterol were reported in the adrenals of 

 non-pregnant female rabbits, as compared with the values for the bucks. 

 This difference largely disappeared in pregnant rabbits. 314 



h. The Maternal-Fetal Transfer of Lipids. The question as to whether 

 or not a transfer of lipids from the maternal blood to the fetus occurs has 

 been answered both negatively and affirmatively. The experimental pro- 

 cedures employed to investigate this question have usually involved the 

 feeding of fats having a fatty acid composition differing from that normally 

 found in the animal. In the case of dogs, Thiemich 315 was unable to demon- 

 strate that feeding cocoa butter or a highly unsaturated fat such as linseed 

 oil to the mothers exerted any influence on the iodine number of the fats in 

 the pups. However, this worker 316 later observed that unsaturation had 

 some effect on the composition of fetal fat; therefore, he concluded that 

 fetal fat may, in part, be derived from maternal fat. Hofbauer 317 also 

 reported the presence of lauric acid in the fetal fat after feeding coconut 

 oil to pregnant guinea pigs. However, other workers have questioned the 

 methods of analysis employed. 318,319 



309 E. M. Boyd, Am. J. Obstet. Gynecol, 29, 797-805 (1935). 



310 J. P. Peters, M. Heinemann, and E. B. Man, J. Clin. Invest., 30, 388-394 (1951). 



311 T. Oshima, Zentr. Physiol, 21, 297-301 (1907). 



312 R. Coope and V. H. Mottram, J. Physiol, 49, 23-33 (1914). 



313 C. Kaufmann and R. Erdmann, Biochem. Z., 249, 438-442 (1932). 



314 E. N. Chamberlain, /. Physiol, 68, 259-264 (1929). 



315 M. Thiemich, Zentr. Physiol, 12, 850-852 (1898). 



316 M. Thiemich, Jahrb. Kinderheilk., 61, 174-177 (1905). 



317 J. Hofbauer, Biologie der menschlichen Plazenta, W. Braumiiller, Vienna-Leipzig. 

 1905, p. 87, 88. 



318 L. G. Wesson, Bull Johns Hopkins Hosp., 88, 237-241 (1926). 



319 J. Needham, Chemical Embryology, Cambridge Univ. Press, Vol. 2, 1931, p. 1192. 



