Effects of maternal hyperoxia on the fetus: I. Oxygen tension☆

Abstract One hundred per cent oxygen was administered to 20 patients during labor for at least a period of 60 minutes. Simultaneous fetal scalp blood samples and maternal arterial blood samples were obtained prior to oxygen administration at 15, 30, 45, and 60 minutes of maternal hyperoxia and after oxygen was discontinued by 5 to 30 minutes. All patients had continuous fetal heart rate, uterine contractions, and maternal blood pressure recording. A statistically significant rise in fetal Po 2 was observed during maternal hyperoxia with a return to initial levels after oxygen was discontinued. The rise in fetal Po 2 blood was not proportional to the increase in maternal Po 2 . There was no associated acidosis observed with the procedure.