Fetal Oxygen Saturation During Maternal Bearing Down Efforts in the Second Stage of Labor

ABSTRACT

Fetal oxygen saturation (FSpO₂) was monitored with the Nellcor Puritan Bennett N400/FS14 system during 16 labors to establish whether FSpO₂ was influenced by maternal bearing down efforts in the second stage of labor. Fetal SpO₂ is reported for 16 fetuses where neonatal outcome was normal. One hour of continuous data was recorded: 30 min prior to the onset of maternal bearing down efforts and the first 30 min of pushing. The hour was divided into six epochs of 10-min duration. Differences between mean FSpO₂ for the two 30 min of monitoring and for each epoch were sought using repeated measures analysis of variance (ANOVA). The mean FSpO₂ for the total 30 min prior to the onset of pushing was 49% (95% confidence intervals 46.5-50.6%), compared to a mean of 46% (95% confidence intervals 43.6-48.7%) during the first 30 min of pushing [F(1, 2.25), p = 0.14]. There was no significant decline in mean FSpO₂ for each epoch. Apgar scores at 5 min were all >7 and umbilical arterial pH values were ≥7.20 (n - 12). We concluded that mean FSpO₂ recorded prior to the onset of maternal bearing down efforts was not significantly different to mean FSpO₂ during pushing, with normal neonatal outcome.

Keywords

Fetal pulse oximetry - intrapartum monitoring