OBJECTIVE: The aim of the study was to evaluate the impact of different concentrations of inspirated O2 on the SpO2 values of the foetus and the mother during the 1st and 2nd stages of labor. DESIGN: Prospective study. SETTING: 1st 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 entrainment O2 mask and the inflatable face mask during 1st and 2nd stages of labor. RESULTS: No changes in maternal SpO2 values were revealed in the three different O2 inspiration regimens neither in the 1st, nor in the 2nd 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 1st stage of labour. These values have decreased promptly after the cessation of the O2 inspiration. The mean SpO2 values at room O2 concentration were 46.3% +/- 7.9 SD for the 1st stage of labor and 43.7% +/- 4.8 SD for the 2nd 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 1st stage of labor. We were not able to evaluate the impact of the O2 inspiration on foetal SpO2 values during the 2nd stage of labor.

1 gynekologicko porodnická klinika Masarykova univerzita Brno