Within the last ten years several groups adapted pulse oximetry to be used in the fetus. The obvious advantage of this technology is the fact that a biochemical parameter--the arterial oxygen saturation--can be measured continuously during delivery. Nevertheless, the continuous information about the fetal oxygenation during delivery has a couple of obstacles to surmount. It is well known that fetal reflectance pulse oximetry may be influenced by a number of artifacts. In addition, severe physiological considerations should remind us of the limited diagnostic value of saturation monitoring alone in order to predict fetal acidosis. Some recent articles deal with the predictive value of fetal pulse oximetry for fetal compromise. While it appears that the fetal wellbeing is more likely to be in accordance with a normal saturation measured by current pulse oximetry systems, the number of fetuses detected by pulse oximetry suffering from hypoxia seems to be low. Different authors describe a poor sensitivity to predict fetal compromise. One reason therefore may be the reduced precision of the oxysensor in the low saturation range. Therefore, we conclude that the current generation of fetal pulse oximetry sensors is not improving the quality of combined fetal monitoring of fetal heart rate and fetal scalp blood analysis.