FETAL OXYGEN CONSUMPTION IN LATE GESTATION

¹ Department of Obstetrics and Gynecology, University of Florida School of Medicine, Gainesville, Florida

In acute experiments the oxygen consumption (ml./min) of pregnant, lightly anesthetized ewes has been determined under steady state conditions before and after occlusion of the umbilical circulation with the fetus in utero. At the conclusion of the experiment the fetus was delivered and weighed. The regular decrease in oxygen consumption which occurred with this procedure was linearly related to the fetal weight over a 4 kg range. On the assumption that this decrease represented the oxygen consumption of the fetus during the control period, the rate of fetal oxygen consumption ranged from 7·7 to 11·3 ml./kg/min. These results are in good agreement with those previously obtained when the umbilical blood flow was estimated and the (V-A)O2 determined across the umbilical circulation with the fetus in utero. They indicate that the oxygen consumption of the near term fetal lamb represents a significant fraction of maternal (6 to 22 per cent in this series) and is of the same order of magnitude as that of the newborn animal.

Note:

Our thanks are due to Professor Harry Prystowsky for his help and cooperation whilst this research was in progress, and one of us (J. F. C. III) is especially grateful to him for the privilege of working in this Department.

This study was aided by grants from the National Institutes of Health and the Association for the Aid of Crippled Children.