New computerized fetal heart rate analysis for surveillance of intrauterine growth restriction

Decreased fetal heart rate variability is associated with higher perinatal morbidity and mortality in intrauterine growth restriction (IUGR). This study used a new method [phase-rectified signal averaging (PRSA)] to calculate acceleration- and deceleration-related fluctuations of the fetal heart rate.

Cardiotocograms from 74 growth-restricted and 161 normal fetuses were included. Both groups were matched for gestational age. The transformed PRSA signal was quantified by the acceleration-related parameter-averaged acceleration capacity (AAC) and compared to the standard short-term variation (STV). Mann-Whitney test and receiver operator characteristic (ROC) curves were used for statistical analysis.

For AAC, the median values of the IUGR group and control group were 1.97 bpm [interquartile range (IQR): 1.66-2.23] and 2.49 bpm (IQR: 2.24-2.72), respectively. For STV, these values were 5.44 ms (IQR: 4.49-7.38) and 7.79 ms (IQR: 6.35-9.66), respectively. The area under the ROC curve was 81.4% for AAC and 70.5% for STV.

The results of AAC are in both groups comparable to STV. Longitudinal studies are needed to investigate the association of AAC with the clinical outcome of the newborn.