A Continuous Smart Abdominal Fetal Heart Rate Monitor using Photoplethysmography

This paper describes a non-invasive optical method for monitoring the fetal heart rate continuously to ensure the fetus and mother's health. It constitutes of an IR emitter (880nm) and a photodiode to detect the fetal heart rate at the mother's abdomen. The photodiode detects the signal of both mother and fetus. We store, analyze, and extract fetal heart rate data from abdominal and finger photoplethysmography (PPG) signals using discrete wavelet transform and recursive least squares adaptive filtration. The proposed device is tested with a cardiotocography (CTG) system, on 30 pregnant women in second and third trimester. A correlation coefficient of 0.967 and a Bland Altman statistic plot p-value of 0.038 are found for CTG and our device. This study also provides the design and implementation of wireless fetus data transmission interfaced through Unity-designed mobile application, accurately and non-invasively. The suggested low-cost system has low power consumption, affordability, a high signal-to-noise ratio, low sensitivity to ambient light, and patient friendliness.