Computerized fetal heart rate monitoring subpartum as a predictor for extreme fetal outcome

Objective: We investigated to what extent subpartum computerized fetal heart rate analysis according to the FIGO criteria can predict fetal outcome. Additionally, we aimed at identifying factors which might be able to explain extreme differences between CTG classification and the actual fetal condition at delivery.

Methods: We screened all 3.380 births from 2000–2002 for extreme good and extreme poor outcomes defined by umbilical artery pH, base deficit and the apgar-score. General boundery conditions for both groups were single fetuses of ≥37 weeks gestational age, vaginal delivery and a CTG record of ≥30min duration ending at least 30min before delivery. The computerized analysis of the CTG was based on the intrapartum FIGO criteria, each separately classified as normal, suspicious or pathological.

Results: 47 cases and 112 controls were selected. The two groups where different with respect to decelerations (p=0.011, Cochran-Armitage-Test) and the overall FIGO score (p=0.024). The value of the FHF baseline (p=0.392) is the least sensitive factor for predicting the fetal condition. However, a total of 35 patients (22%) were extremely misclassified in either direction. These patients were investigated further to reveal potential error sources, influence factors or just artefacts. Some explanations found might become useful in enhancing the predictive value of FHR monitoring.