Assessment of fetal development using Multiscale Multifractal Analysis of heart rate variability

The two lowest bands (very low frequencies and ultralow frequencies) of human heart rate variability (HRV) account for 95% of the total signal power. The underlying physiological processes are heterogeneous and complex. Hence, frequency band power analysis can be expected to be an over-simplification. Recently fractal scaling methods, such as DFA have been used to analyze fetal heart rate fluctuations [1]. In our study, we assessed 132 magnetocardiographic heart beat interval series. 30 minute signals were recorded from fetuses of 21-38 weeks of age. A novel method was employed for analyzing the data: Multiscale Multifractal Analysis (MMA) [2]. As a result of the method, we obtain the Hurst surface which describes, in a very compact form, the fluctuation scaling properties (i. e. nonlinear correlation properties) depending on the fluctuations magnitude and frequency range (scale). Note that the MMA method is designed specifically to analyze the VLF band of heart rate variability. Using the MMA method, we developed a statistical model which is able to predict gestational age based only on the magnetocardiographic recordings [3]. We hope that our work will provide a significant input to noninvasive, efficient and accurate prenatal diagnosis methods.