THE EFFECT OF MATERNAL OXYGEN ADMINISTRATION DURING THE 2ND STAGE OF LABOR ON UMBILICAL-CORD BLOOD-GAS VALUES - A RANDOMIZED CONTROLLED PROSPECTIVE TRIAL

OBJECTIVE: Our aim was to determine whether supplemental oxygen during the second stage of normal labor affects cord blood gas and cooximetr y values. STUDY DESIGN: Patients at term pregnancy were prospectively randomized to the control or treatment group at the onset of the secon d stage of labor. The treatment group received 10 L/min oxygen by face mask, which result in a mean fractional inspired oxygen concentration of 0.81. RESULTS: There were 86 patients randomized into the study. I n the oxygen group there were significantly more cord arterial pH valu es < 7.20 (9/41 vs 2/44, p < 0.05). The control group was compared wit h two subgroups of patients receiving oxygen: those receiving oxygen t herapy for less than or equal to 10 minutes and those receiving oxygen for > 10 minutes. Analysis of variance demonstrated significant diffe rences (7.285 +/- 0.058, 7.312 +/- 0.056, 7.237 +/- 0.064; F test 8.3, p = 0.0005). Among several independent variables, regression analysis demonstrated that only duration of oxygen therapy had a significant i nverse relation to cord arterial pH (F test = 15.6, p = 0.0002). CONCL USIONS: Prolonged oxygen treatment during the second stage of normal l abor resulted in a deterioration of cord blood gas values at birth.