A novel approach for extraction and analysis of variability of baseline

Cardiotocography or CTG, is a technical means of continuously recording (-graphy) the fetal heart beat (-cardio) and the uterine contraction (-toco) of the mother. CTG is non-invasive, low price tool for checking the fetal status. Its introduction to the clinical routine limited the occurrence of fetal damage such as cerebral palsy as well as fetal mortality. One of the major features of fetal heart rate (FHR) is its baseline. Visual analysis by expert clinicians is used to evaluate the FHR baseline. This results in large inter and intra-observer variability in its interpretation. There are continuous efforts to develop methods to more accurately predict the baseline of FHR. There exist a relationship between FHR and the uterine contraction. In this paper we have explored effect of uterine contraction on the heart rate of the fetus and hence on the value of the baseline. Baseline is calculated by removing the acceleration, deceleration, and the portion of FHR which corresponds to uterine contraction. Depending on this value of baseline variability is calculated and classified. Our results were compared with the opinions of an obstetrician and another researcher in this field.