Perinatal oxygen environment

Abstract 1.1. A method of direct polarographic determination of oxygen tension of fetal blood and of amniotic fluid is described. 2.2. The mean oxygen tension of umbilical fetal blood was found to be 29.5 mm. Hg in 21 umbilical veins and 12.1 mm. Hg in 21 umbilical arteries of normal newborn infants following 21 uncomplicated spontaneous pelvic deliveries without inhalation anesthesia or prophylactic oxygen administration. 3.3. The mean oxygen tension of amniotic fluid from 19 normal pregnant women at term was 25.5 mm. Hg. 4.4. The data suggest that the fetal oxygen environment in utero is hypoxic only when compared with adult criteria for extrauterine existence. 5.5. A suggestion is offered that the fetal capacity to tolerate hypoxia or anoxia may not be a matter of fetal adaptability but an expression metabolically of different biologic needs.