Fetal Oxygen Saturation Monitoring in Labour: An Analysis of 118 Cases

Summary: Fetal oxygen saturation (FSpO₂) was recorded during labour to determine the relationship between FSpO₂ and indicators of fetal well-being, including umbilical blood gases, xanthine (X), hypoxanthine (Hx) and Apgar scores. This is one of me largest reported series of fetal pulse oximetry, with 118 fetuses monitored for over 329 hours. Mean FSpO, for all cases was 46.9% (SD=9.1%). There was no correlation between FSpO, during the last 10 minutes of monitoring and arterial pH, Hx or X. A mean FSpO₂, ≤ 30% was associated with a 5 minute Apgar score of ≤ 7 in the majority of cases. One fetus had a mean FSpO₂, <30% during the final 10 minutes of monitoring and an umbilical arterial pH<7.20, while there were 10 fetuses with an umbilical arterial pH<7.20, and mean FSpO₂, ≥ 30%. As these numbers are small, a larger series is necessary to further characterize the small number of fetuses who are significantly hypoxic.