Continuous subcutaneous pH measurement in human fetuses: correlations with scalp and umbilical blood pH.

The subcutaneous pH values of 42 fetuses has been measured continuously during labor with the use of the electrode designed by Stamm and associates. We have obtained 60 per cent good tracings. The results have confirmed the reliability of the subcutaneous pH measurement, if the electrode is correctly inserted, when compared with both capillary and umbilical artery blood pH measurements (r = 0.91, p less than 0.001 and 0.83, p less than 0.001, respectively). Technical improvements appear to be necessary prior to widespread clinical use of continuous pH measurement.