The influence of events during the last few days in utero on tissue destruction and renal function in the first two days of independent life.

Since women do not begin to secrete milk freely till the third day after delivery, and no other food is available in nature for the baby, its life is maintained during the first two days after birth largely at the expense of its own tissues, and some destruction of body protein and fat is inevitable. The extent of this protein breakdown was measured by McCance and Strangeways (1954) in six normal full-term babies over the first 48 hours of their lives. During this time the infants were given 25-50 ml. of water but no food, and their basal metabolic rates (B.M.R.) were determined at intervals. The net amount of nitrogen (N) appearing in the form of end-products varied from 49 to 108 and averaged 75 mg./kg./24 hr.; the B.M.R. averaged 50 K Cals/kg./24 hr. The latter is close to the figures obtained by others. In the course of this work one baby was studied (No. 2 in the present series) who had been born after a very difficult labour and who was post-mature. His blood urea level rose to 106 mg./100 ml. and his net catabolism of protein set free 190 mg.N/kg./24 hr. This was considered in all probability to be unphysiological and the baby was excluded from McCance and Strangeways' normal series. It was thought at the time that events during the last few days in utero might have been responsible for the high rate of protein breakdown. The matter has now been further investigated and the results form the basis of this paper, but since the B.M.R. of the baby studied by McCance and Strangeways (1954) was perfectly normal (47 5 K Cals/kg./24 hr.), and since such determiinations are extremely difficult and laborious, no further work has up to the present been done on them. Aspects of renal function in premature infants during the first few days of life have been studied by Smith, Yudkin, Young, Minkowski and Cushman (1949), in premature and full-term infants by Hansen and Smith (1953) and in healthy full-term infants also by Thomson (1944, 1949) and McCance and Widdowson (1954a). The studies of McCance and Widdowson were conducted concurrently with the ones now being described, and the findings have provided standards of normality with which to compare the present ones.