What is the normal range of oxygen saturation of the fetus during labor?
Information available regarding the “normal” range of fetal arterial oxygen saturation during labor comes from laboratory studies conducted on animals and from fetal pulse oximetry studies on humans. Animal studies, in which preductal arterial blood samples are drawn, find normal fetal saturations range from 30% to 70%. Even when the maternal ewe is ventilated with 100% oxygen, fetal saturations have not exceeded 86% under stable conditions11. For humans, in a series of 87 normal labors with normal outcomes, the mean FSpO2 was 47% (+8.4%). Using prototype designs on humans, investigators have noted a steady decline in baseline saturations as labor progresses, generally 5% to 10% from early to late labor.
Information available regarding the “normal” range of fetal arterial oxygen saturation during labor comes from laboratory studies conducted on animals and from fetal pulse oximetry studies on humans. Animal studies, in which preductal arterial blood samples are drawn, find normal fetal saturations range from 30% to 70%. Even when the maternal ewe is ventilated with 100% oxygen, fetal saturations have not exceeded 86% under stable conditions11. For humans, in a series of 87 normal labors with normal outcomes, the mean FSpO2 was 47% (+8.4%).
