Objective: The aim of the study was to evaluate the impact of different concentrations of inspira- ted O2 on the SpO2 values of the foetus and the mother during the 1 st and 2 nd stages of labor. Design: Prospective study. Setting: 1 st Department of Gynecology and Obstetrics, Medical Faculty of Masaryk University, Brno Methods: 17 non-risk patients were enrolled in the study. The SpO2 levels of the mother and the foetus were monitored simultaneously in 10 min intervals with the room air inspiration entrain- ment O2 mask and the inflatable face mask during 1 st and 2 nd stages of labor. Results: No changes in maternal SpO2 values were revealed in the three different O2 inspiration regimens neither in the 1 st , nor in the 2 nd stages of labor. The mean value was 98 % ± 1.6 SD. As for the foetus the SpO2 values were increased by 6 % (± 7.9 SD) after 40 % concentration of O2 and 7.7 % (± 8.8 SD) after 98 % O2 inspiration during the 1 st stage of labour. These values have decrea- sed promptly after the cessation of the O2 inspiration. The mean SpO2 values at room O2 concen- tration were 46.3 % ± 7.9 SD for the 1 st stage of labor and 43.7 % ± 4.8 SD for the 2 nd stage of labor. Conclusion: The O2 inspiration during the labor has no impact on the maternal SpO2 values but increases the SpO2 values of the foetus during the 1 st stage of labor. We were not able to evaluate the impact of the O2 inspiration on foetal SpO2 values during the 2 nd stage of labor.

        Key words: O2 inspiration, no risk pregnancy, intrapartum foetal pulse oximetry, oxygen satura- tion