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

TL;DR

This study investigates how a Yoga intervention influences heart rate variability patterns in stressed pregnant women, revealing dynamic changes across pregnancy and suggesting Yoga's potential to modulate maternal autonomic regulation.

Contribution

It introduces a comprehensive HRV analysis framework combining multiple metrics and PCA to assess Yoga's impact on maternal autonomic regulation during pregnancy.

Findings

HRV relationships shift from frequency to complexity measures late in pregnancy

Significant time x group interaction effect (p=0.041) indicating Yoga influences HRV patterns

Advanced HRV analysis can detect intervention-related changes in maternal autonomic regulation

Abstract

Prenatal maternal stress (PS) is a risk factor for adverse offspring neurodevelopment. Heart rate variability (HRV) complexity provides a non-invasive marker of maternal autonomic regulation and may be influenced by mind--body interventions such as Yoga. In this quasi-randomized controlled trial, 28 chronically stressed pregnant women were followed from the second trimester until birth: 14 participated in weekly Hatha Yoga with electrocardiogram (ECG) recordings, and 14 received standard obstetric care with monthly ECGs. Group allocation was based on availability, with participants unaware of their assignment at enrollment. HRV complexity was assessed first with Sample Entropy and Entropy Rate and then expanded to 94 HRV metrics spanning temporal, frequency, nonlinear, and information-theoretical domains. All metrics were covariate-adjusted (maternal age, BMI, gestational age), standardized, and analyzed using timepoint-specific principal component analysis (PCA). From this, a unified HRV index was derived. Analyses revealed that HRV metric relationships changed dynamically across pregnancy, with PCA loadings shifting from frequency toward complexity measures in late gestation. The mixed effects model identified a significant time x group interaction effect (p = 0.041). These findings suggest a restructuring of HRV signal-analytical domains with advancing pregnancy attributable to Yoga and highlight the utility of advanced HRV analysis frameworks for future, larger trials.