Simulation of FHR Signals with Abnormal Variability Ushasri Akkanapalli 1 , Dr. Malini Mudigonda 2 , Sai Sreeja Samavedam 3 and Meghana Koppadi 4 1-4 Department of Biomedical Engineering, University College of Engineering, Osmania University, Hyderabad, India Email: usha.chary@gmail.com, malini.m@uceou.edu, saisreejas.be23@uceou.edu, meghanak.be23@uceou.edu Abstract—Cardiotocography or CTG is usually performed by obstetricians to examine fetal well-being during or before labor. Generally, visual inspection of the trace is performed to analyze the fetal heart rate signal, but due to its highly subjective nature, it lacks specificity and reproducibility. Computerized analysis of the trace provides a more objective standpoint for the identification and interpretation of various physiological and pathological conditions in the fetus. However, abnormalities in the trace are generally hard to come by. In the present paper, we have developed an algorithm for the simulation of FHR signals with abnormal variabilities using three distinct patterns. This algorithm was implemented on the CTG records of 57 subjects collected from hospitals. The morphological features of both original and simulated signals were plotted and the results were tabulated. Index Terms— Cardiotocography, Morphological features, Simulation, Floating line, Gaussian tract and Fetal heart rate. I. INTRODUCTION Cardiotocography or CTG is the simultaneous recording of Fetal Heart Rate (FHR) and Uterine Contractions (UC) used in clinical practice for fetal health monitoring. It is the most diffused technique for both in antepartum and intrapartum periods to assess fetal well-being and to avoid fetal death due to birth asphyxia [1]. Obstetricians generally rely on visual inspection of the CTG trace to analyze and diagnose anomalies in the signal. This method of interpretation is subject to intra- and inter-observer variability as shown by several FHR reliability studies [2, 3]. Therefore, to overcome these shortcomings, a computerized analysis of the CTG trace was developed to assist clinicians in the identification of various physiological and pathological events during labor. The commonly evaluated features from the FHR signal in clinical settings are baseline, baseline variability, accelerations and decelerations, collectively referred to as morphological features.  Baseline is defined as the mean FHR within a 5-10-minute window ignoring any accelerations and decelerations.  Baseline Variability, more commonly called Fetal Heart Rate Variability (FHRV), are the oscillations in the signal around the baseline in amplitudes of 5-25 beats per minute (bpm).  Accelerations correspond to elevations in the signal of at least 15 bpm greater than the baseline and last for not less than 15 seconds.  Decelerations are the nadirs (lowest points) in the signal of at least 15 bpm less than the baseline and lasting for more than 15 seconds. These definitions of the morphological features are in accordance with the guidelines dictated by the Royal Grenze ID: 01.GIJET.8.2.502 © Grenze Scientific Society, 2022 Grenze International Journal of Engineering and Technology, June Issue