Analysis of the AAC and ADC as recorded with a high resolution fECG recorder may differentiate better between normal and SFD fetuses than STV.

Aim. There is no consensus about the normal fetal heart rate. Current international guidelines recommend for the normal fetal heart rate (FHR) baseline different ranges of 110 to 150 beats per minute (bpm) or 110 to 160 bpm. We started with a precise definition of “normality” and performed a retrospective computerized analysis of electronically recorded FHR tracings.Methods. We analyzed all recorded cardiotocography tracings of singleton pregnancies in three German medical centers from 2000 to 2007 and identified 78,852 tracings of sufficient quality. For each tracing, the baseline FHR was extracted by eliminating accelerations/decelerations and averaging based on the “delayed moving windows” algorithm. After analyzing 40% of the dataset as “training set” from one hospital generating a hypothetical normal baseline range, evaluation of external validity on the other 60% of the data was performed using data from later years in the same hospital and externally using data from the two other hospitals.Results. Based on the training data set, the “best” FHR range was 115 or 120 to 160 bpm. Validation in all three data sets identified 120 to 160 bpm as the correct symmetric “normal range”. FHR decreases slightly during gestation.Conclusions. Normal ranges for FHR are 120 to 160 bpm. Many international guidelines define ranges of 110 to 160 bpm which seem to be safe in daily practice. However, further studies should confirm that such asymmetric alarm limits are safe, with a particular focus on the lower bound, and should give insights about how to show and further improve the usefulness of the widely used practice of CTG monitoring.

Objective  To identify sensitivity and specificity of computerised cardiotocography (CTG) analysis for fetal acidosis during delivery. Design  Retrospective observational study. Setting  Tertiary referral labour ward, Technical University München (TUM) and University Witten/Herdecke (UWH). Population  All deliveries, which had at least one fetal scalp pH measurement and electronically saved CTG traces, between 2000 and 2002 (TUM) and between 2004 and 2005 (UWH). Method  Correlation analysis of fetal scalp pH values and computerised International Federation of Obstetrics and Gynecology (FIGO) classification using ‘CTG Online®’ program of digitally saved CTG traces. Main outcome measures  Fetal scalp pH values, FIGO parameter (baseline, variability, acceleration and deceleration) using computerised analysis. Results  Both collectives showed a high sensitivity (95.0%) for computerised FIGO classification ‘suspect’ and ‘pathological’, together with a low specificity (21.8%) for fetal acidosis. The most sensitive single FIGO parameter was deceleration. Very low sensitivity (<50%) was shown for the parameters variability and acceleration. Conclusions  Computerised CTG analysis is highly sensitive for fetal acidosis and can be used as an objective adjunctive criterion during delivery. Further CTG data are needed to adjust and optimise each FIGO parameter and increase sensitivity and specificity.

AAC shows an improvement to discriminate between normal and compromised fetuses at a single moment in time, in comparison with STV.