Insufficiency of O₂ supply to pregnant uterus

¹ Department of Medicine, Boston University School of Medicine; Department of Medicine, Harvard Medical School, Boston, Massachusetts; and Department of Physiology, Yale School of Medicine, New Haven, Connecticut

Pregnant goats under anesthesia were studied while subjected to various degrees of hypoxemia. Lactate and pyruvate concentrations were determined in maternal arterial and uterine venous bloods and in umbilical arterial and venous bloods. The same highly heterogeneous values were found as reported for nonhypoxemic animals, and no clear systematic relationships could be discerned. However, when the values were viewed as being determined by exchanges of excess lactate on each side of the placenta, several patterns of metabolic activity were discernible. 1) No net anaerobic metabolism occurred in the pregnant uterus in the well-oxygenated mother. 2) When maternal blood oxygen was extremely low, anaerobic metabolism occurred in the fetus and in the uterus as a whole. 3) However, in the whole range of mild and moderate hypoxemia, the pattern consisted of production of excess lactate by the fetus and its reoxidation by the placenta; consequently, there was no net anaerobic metabolism by the pregnant uterus as a whole. Such fetuses, even when umbilical blood oxygen was virtually absent, survived and showed no signs of deleterious effect.

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				G. M. Folger JR Acidemia of Cardiogenic Origin in Young Infants with Cyanotic Congenital Heart Abnormalities: Pathogenesis, Diagnosis and Treatment, with Particular Emphasis on Neonatal Acid-base Disturbance Clinical Pediatrics, October 1, 1972; 11(10): 573 - 579. [PDF]