Heart Rate Variability Patterns Reflect Yoga Intervention in Chronically Stressed Pregnant Women: A Quasi-Randomized Controlled Trial

Figures

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  Figure A1. Delta analyses show the entropy differences from the beginning to the end of the study, with the aim of showing Yoga intervention-related changes. We assessed the Delta values both at baseline before the Yoga lesson/at the beginning of the recording as well as after the Yoga lesson/at the end of the recording.

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  Figure 1. Recruitment flow chart.

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  Figure 2. Electrocardiogram’s (ECG) time windows of an individual experiment chosen for the entropy analyses. Dark red is the preferred time window; light red is the alternative time window when the signal quality of the other window was not sufficient. Pictures are AI-generated. Our goal was to choose baseline or the latest possible recovery segments to avoid signal contamination by exercise.

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  Figure 3. Sample Entropy (SampEn) and Entropy Rate in the second (“begin”) and last (“end”) 10-min time windows are compared between the groups (Yoga vs. control) and during pregnancy. Blue (pink): first (last) session for the Yoga group; green (light green): first (last) session for the control group. At the first session, both entropy biomarkers were already higher in the Yoga group compared to the control group. By the end of the study, the Entropy Rate had further increased in the Yoga group, while it remained stable in the control group. Red straight line in the box plots indicates the median.

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  Figure 4. Comprehensive HRV analysis in pregnancy: correlation structure, PCA, domain contributions, and longitudinal modeling. (A,B) Correlation matrices of representative HRV metrics at the first visit (A) and last visit (B). Colors indicate correlation coefficients from −1 (blue) to +1 (red). (C,D) Principal component analysis (PCA) loadings for the first principal component (PC1) at the first (C) and last (D) visits. HRV metrics are grouped by physiological domains: Time (green), Frequency (orange), Complexity (red), Specialized (purple), and Information-theoretic (dark red). (E) Cross-timepoint comparison of domain contributions to PC1 between the first and last visits. (F,G) Distribution and longitudinal trajectories of the unified HRV index for the Yoga group (F) and Control group (G). (H) Results of linear mixed-effects models on the unified HRV index, showing standardized coefficients for group, time, and interaction terms.