Placental transfer in normal and toxic gestation

Abstract

1.1. Transabdominal aspiration of blood from the intervillous space at varying intervals after the intravenous injection of antipyrine shown that the concentration of antipyrine in intervillous blood has a mean value of 98 per cent of that in peripheral venous blood with a standard deviation of 8 per cent. This circumstance is analyzed in terms of the anatomy and physiology of the circulations to the placenta.2.2. A method is presented for the calculation of the instantaneous intervillous concentration of antipyrine from the peripheral venous concentration.3.3. Comparison of the concentrations of antipyrine in the umbilical vein with the calculated simultaneous intervillous concentration indicates that, in the time maternal and fetal blood are exposed at the placental barrier, equilibration of antipyrine is complete.4.4. Similar studies employing sodium24 indicate that the diffusion of charged particles is impeded.5.5. In similar studies on patients with toxemias of pregnancy, no constant relationship is found between intervillous and peripheral venous concentration of either antipyrine or sodium.6.6. The data from toxemic patients are analyzed in terms of possible anatomic and vascular changes that may occur in toxemia.