Fetal pulse oximetry. A methodogical study

During recent years fetal pulse oximetry has been under development for use in monitoring fetal oxygenation during labor. In a methodological study we have tested the practical applicability of one type of sensor (FS-10 Oxisensor, Nellcor). Both obstetricians and midwives took active part in sensor placement. The readings of fetal arterial oxygen saturation (SpO2) were not taken into account when managing the patients.

Oxygenation was monitored during labor in 96 singleton pregnancies. Mean SpO2 levels were calculated when cervical dilatation was 4-7 cm and 8-10 cm, and in the second stage of labor. Student's t-test was used for paired comparisons. A p-value<0.05 was considered significant.

Of the 96 oxisensors, 91 (95%) were successfully placed. One mother felt pain which disappeared when the sensor was removed. Two of the newborns manifested an impression mark caused by the sensor, which disappeared completely within a day. No infection or increased bleeding was noted. The mean recording time was 134 minutes. SpO2-values were obtainable during 69% of the recording time. A significant fall of mean SpO2 occurred between the first and second stages of labor.

The method seems to be harmless for mother and child, and allows SpO2-values to be obtained during two thirds of the recording period. Further research is needed to evaluate the possible clinical value of the method.