Computerised analysis of antepartum foetal heart parameters: New reference ranges

We selected 4012 cCTG records (one trace for each patient) performed in healthy pregnancies from 30th to 42nd gestational week using foetal heart rate (FHR), short-term variability (STV), long-term irregularity (LTI), Delta, approximate entropy (ApEn), spectral components as low frequency (LF), median frequency (MF), high frequency (HF) and LF/(HF + MF) ratio were analysed. Reference nomograms were created and sensitivity and specificity for the prediction of foetal compromise were calculated which were 90% and 89%, respectively. Changes of cCTG parameters according to gestational week were evaluated: FHR (r = −.65) and LF (r = −.87) showed a statistically significant reduction (p <.05) with gestational age. STV (r =.59), LTI (r =.69), Delta (r =.67), and MF (r =.88) showed a statistically significant increase (p <.05) with gestational age. In contrast, for ApEn (r = −.098), HF (r =.14) and LF/(HF + MF) ratio (r = −.47) a non-statistically significant change was found (p >.05). The identification of reference ranges for cCTG indexes in according to gestational age could provide a more objective examination of cCTG trace.