Changes of fetal oxygen saturation (SpO₂) during labor and maternal oxygen administration effect on fetal SpO₂

Summary

We adapted a newly developed reflectance pulse oximeter probe to the fetal forehead in order to monitor fetal oxygen saturation (SpO₂) during labor. In addition, maternal oxygen administration was performed and fetal SpO₂ measured to evaluate its effects.

120 patients who came to labor from 36 to 41 weeks of gestation were measured. Reflectance pulse oximeter probe was adapted to the fetal forehead on the condition that the uterine cervix was dilated over 4 cm with rupture of the bag.

• 1) The average fetal SpO₂ was 56 % to 60 % in the first and second stage of labor and 48 % immediately before delivery.

• 2) By conducting maternal oxygen administration during labor at 5 1/min, we confirmed that in cases where SpO₂ was under 50 % with oxygen administration, SpO₂ rose over 10 % above previous levels. On the other hand, in cases with SpO₂ over 60 % there was no change. In this study, we were able to clarify the average fetal SpO₂ at the time of normal delivery. Furthermore, it was also confirmed that oxygen administration was effective in cases of fetal SpO₂ of under 50 %.