980 



SPERM, OVA, AND PREGNANCY 



imately the 4th month of pregnancy (Rowe 

 and Boyd, 1932; Javert, 1940). No other 

 sym})toms of hyperthyroidism are seen in 

 pregnancy which leads to the question of 

 the significance of the rise in protein-bound 

 iodine. A somewhat comparable paradox 

 exists in the guinea pig in which a rise in 

 the rate of oxygen consumption during 

 pregnancy is not accompanied by an in- 

 crease in heart rate (Hoar and Young, 

 1957). 



Recently, AVerner (1958) rcj^orted a de- 

 crease in the I^-^^ up-take after treatment 

 with triiodothyronine in both the normal 

 and pregnant woman. From this and other 

 data he ruled out any abnormal pituitary- 

 thyroid relationship or marked secretion of 

 thyroid-stimulating hormone (TSH) by the 

 placenta and concluded that the increased 

 PBI in pregnancy is due to an increased 

 binding capacity of the serum protein. 



Feldman ( 1958) failed to find any increase 

 in the level of serum-hutanol-extracted io- 



dine throughout pregnancy in the rat. Ac- 

 tually the values were consistently lower 

 than in the controls and similarly the total 

 amount of PBI in the thyroid of the preg- 

 nant rat was consistently lower. He did find 

 an increase in the rate of excretion of V-''\ 

 a diminished up-take of I^^^ by the thyroid, 

 and a decreased half-life for thyroxine in the 

 pregnant rats. It is obvious that these results 

 are quite dissimilar from those obtained in 

 the pregnant women. One can only conclude 

 at this time that pregnancy has an effect on 

 iodine metabolism and a species difference 

 exists. 



H. GROWTH HORMONE 



Although it has been possible to demon- 

 strate the presence of growth-promoting sub- 

 stance (STH) in the blood plasma, there are 

 few data bearing on the identity of the sub- 

 stance and few ciuantitative measurements. 

 Westman and Jacobsohn ( 1944) first showed 

 the ]irescnce of a growth-]5romoting sub- 



MONTHS 2 



DAYS 



3 4 5 6 7 8 9 



Fig. 16.17. Urinary excretion of aldosterone throughout pregnancy in the human being. 

 O, free fraction only; •, free and acid-hydrolyzed fraction; O, free, enzyme and acid- 

 hA'drolyzed. (From E. H. Venning and I. Dyrenfurth. J. Clin. Endocrinol,, 16, 426, 1956.) 



