FETAL OXYGEN-SATURATION DURING MATERNAL BEARING DOWN EFFORTS IN THE 2ND-STAGE OF LABOR

Fetal oxygen saturation (FSpO(2)) was monitored with the Nellcor Purit an Bennett N400/FS14 system during 16 labors to establish whether FSpO (2) was influenced by maternal bearing down efforts in the second stag e of labor. Fetal SpO(2) is reported for 16 fetuses where neonatal out come was normal. One hour of continuous data was recorded: 30 min prio r to the onset of maternal bearing down efforts and the first 30 min o f pushing. The hour was divided into six epochs of 10-min duration. Di fferences between mean FSpO(2) for the two 30 min of monitoring and fo r each epoch were sought using repeated measures analysis of variance (ANOVA). The mean FSpO(2) for the total 30 min prior to the onset of p ushing was 49% (95% confidence intervals 46.5-50.6%), compared to a me an of 46% (95% confidence intervals 43.6-48.7%) during the first 30 mi n of pushing [F(1, 2.25), p = 0.14]. There was no significant decline in mean FSpO(2) for each epoch. Apgar scores at 5 min were all >7 and umbilical arterial pH values were greater than or equal to 7.20 (n = 1 2). We concluded that mean FspO(2) recorded prior to the onset of mate rnal bearing down efforts was not significantly different to mean FSpO (2) during pushing, with normal neonatal outcome.