Normal range of fetal transcutaneous carbon dioxide tension during labour

Summary. Fetal transcutaneous carbon dioxide tension (tc-Pco), was monitored during 122 deliveries, using an electrode temperature of 44°C in 80 cases and of 41°C in 42 cases. Significant correlations between tc-Pco₂ and umbilical artery blood Pco₂ were found using both electrode temperatures, but the regression lines indicated a larger and more inconstant CO₂-contribution from skin metabolism when the low electrode temperature was used. Normal range of tc-Pco₂ was calculated at 41°C and 44°C electrode temperatures. Mean values of fetal tc-Pco₂ were found to increase during normal labour, and especially in fetuses developing acidosis, but only four of six infants born with acidaemia had tc-Pco₂ values exceeding the normal range.