A Phonography-Based Method Improved by Hidden Markov Model for Fetal Breathing Movement Detection

Marton Aron Goda,Tamas Telek

doi:10.1109/access.2021.3072977

Abstract

This paper proposes a novel phonography-based method for Fetal Breathing Movement (FBM) detection by its excitation sounds. It requires significantly less effort than the current procedures, and it allows long-term measurement, even at home. More than 50 pregnancies in the third trimester were examined, for a minimum of 20 minutes, taking synchronous long-term measurements using a commercial phonocardiographic fetal monitor and a 3D ultrasound machine. To analyze the gained chaotic signal, the frequency band was split into single test-frequencies in the 15–35 Hz frequency band, and their signal-free (silent) zones were regarded as the starting point (SP) of the next motions. The analysis made other disturbing signals, such as fetal hiccups, trunk rotation and limb movements, or maternal heart beats, distinguishable. The dominant test-frequencies of the analysis were predicted by a Hidden Markov Model (HMM). The SPs of the motion units (episodes) were determined by some features of the FBM, applying weighting factors. The recorded material lasted for 16 hours altogether (with nearly 3.5 hours of FBM). Based on the results of HMM method, nearly 7500 FBM episodes were identified in the phonogram signal with an average length of 0.96±0.13 seconds. The procedure for phonography-based breathing movement detection can be combined with a fetal heart activity measurement, and thus allows very intensive, long-term monitoring of the fetus.

Highlights

The widespread popularity of ultrasound imaging resulted in more detailed measurements of fetal activity with a higher resolution and identified the variability of Fetal Breathing Movement (FBM) [1]
New possibilities have since arisen with the improvement of sonography and phonocardiography [3], dealing with special aspects of FBM detection such as the cross-correlation between breathing and Fetal Heart Rate (FHR) variations, The associate editor coordinating the review of this manuscript and approving it for publication was Alessandra Bertoldo
Our measurements proved that the FBM epochs are formed by smaller episode groups

Summary

Introduction

The widespread popularity of ultrasound imaging resulted in more detailed measurements of fetal activity with a higher resolution and identified the variability of Fetal Breathing Movement (FBM) [1]. Early scientific results did not clarify all aspects of FBM, even though it became a meaningful indicator for fetal well-being. This was demonstrated by the Biophysical Profile (BPP), which uses FBM as an important index during pregnancy [2]. New possibilities have since arisen with the improvement of sonography and phonocardiography [3], dealing with special aspects of FBM detection such as the cross-correlation between breathing and Fetal Heart Rate (FHR) variations, The associate editor coordinating the review of this manuscript and approving it for publication was Alessandra Bertoldo. A new technical possibility, the phonographic method [12] has revolutionized the field of fetal measurements

Methods

Results

Discussion

Conclusion