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A method is described for the simultaneous estimation of uterine and umbilical blood flows and oxygen uptakes. A test stubstance, antipyrine, was infused at constant rate in the fetal circutlation. About 50 min. after starting the infusion a steady state was attained in which the rate of transplacental diffusion of the test substance was equal, blut for small corrections, to the rate of infusion. During the steady state, blood samples were collected from uterine and umbilical arteries and veins and analyzed for antipyrine and oxygen. Flows and oxygen uptakes were calculated according to Fick's principle. Thie results of sixteen experiments on sheep and goats sh1ow that: (1) transplacental diffusion of antipyrine is mainly flow‐limited, (2) the placenta simulates a concturrent system of exchange, and (3) the oxygen uptakes of the fetus and the utero‐placental mass were, in many cases, of similar magnitude.
Meschia et al. (Sun,) studied this question.