Fetal pulse oximetry: a new method of monitoring the fetus.

Experimental pulse oximetry devices, similar to the existing systems used in adult and neonatal monitoring, can be used on the fetus to provide safe, and rapid information about oxygenation. They have been calibrated using fetal lambs and validated in human cross-sectional studies. Experiments have shown that fetal oxygen saturation decreases during normal labour, and drops after a uterine contraction especially with oxytocin-induced tachysystole. When the mother is given oxygen the fetal oxygen saturation increases. Readings are effected by caput and movement, and trends seem to be more meaningful than absolute values. Pulse oximetry can predict fetal outcome and a normal oxygen saturation result is specific for a good outcome perhaps even if the CTG is abnormal. However the technique is still experimental and there is insufficient data to support its use as a replacement for fetal blood sampling or a discriminator for an abnormal fetal heart trace.