Correlation of fetal heart rate-uterine contraction patterns with fetal scalp blood pH.

The significance of fetal heart rate-uterine contraction (FHR-UC) monitoring as a means of predicting the condition of the fetus during labor was studied by correlating 460 fetal pH determinations obtained from 216 patients with the analysis of the 20-minute FHR-UC record preceding the fetal scalp blood sample. Both qualitative and quantitative analyses of the FHR-UC record were performed. The results indicate a less than 10% chance of fetal pH less than or equal to 7.250 with an normal baseline FHR and no periodic changes or with periodic accelerations, early decelerations, and uncomplicated baseline bradycardia or tachycardia. Variable or delayed decelerations with a total surface area (TSA) of 1-100 for the 20-min period were associated with a fetal pH less than or equal to 7.250 in 23 and 34% of cases, respectively. Variable or delayed decelerations with a TSA greater than 100 had a 35 or 47% chance of fetal pH less than or equall to 7.250. It is concluded that FHR-UC monitoring can be used to screen the innocuous from the ominous periodic change but that fetal scalp blood pH must be obtained to identify accurately the true from the false-positive ominous pattern.