Continuous fetal tissue pH monitoring in labor with high risk pregnancies.

Continuous tissue pH monitoring was performed in 61 high risk pregnancies in labor. Useful data was obtained in 48 cases, and compared with fetal scalp blood pH and umbilical artery and vein blood pH. The relationshiip of tissue pH and fetal heart rate changes was analyzed. The tissue pH changes occurred within 2--3 min of the fetal heart rate change, and conformed to the expected fetal physiology of their heart rate pattern.