1 Division of Perinatal Medicine, Departments of Obstetrics-Gynecology and Pediatrics, University of Colorado Medical Center, Denver
The flow-limited clearance of 3H2O or antipyrine has been used to define a maximum clearance across the sheep and rhesus monkey placentas. This has served as a reference point for comparison of rates of transfer of other solutes. In addition, these studies have shown that the sheep placenta functions as a concurrent flow system, emphasizing the importance of uterine venous concentrations in interpreting changes in umbilical venous blood.
A description of preparations is provided which permit repeated measurements of fetal and total uterine oxygen consumptions. These preparations have been used to study the effect of maternal hyperoxia, acute exposure to high altitude, and fetal exchange transfusions upon fetal oxygenation.