Investigating asymmetry in fetal and maternal heart rate accelerations and decelerations

This study investigates the asymmetry in heart rate (HRA) during fetal development in the fetus and mother. R-R intervals from noninvasive fetal and maternal ECG signals from 102 pregnant women whose gestational age ranges from 20 to 40 weeks were analyzed. Several HRA indices, which evaluate the accelerations and decelerations in RR interval time-series data, were utilized to examine the variations in HRA in both the fetus and the mother. Results showed that 74.5% of mothers showed asymmetry when measured using index Deceleration Input (DI_D2A). In fetuses, the asymmetry is driven by acceleration-to-deceleration transitions, while in mothers, asymmetry is influenced by deceleration-to-acceleration. Also, phase rectified signal averaging (PRSA) reveals that acceleration and deceleration capacities (AC and DC) show significant correlations with gestational age (GA), indicating that PRSA is a promising tool for assessing fetal development. This study also showed that Porta Index (PI) is associated with sympathetic activity, and the fetal behavioral state influences maternal HRA. This work provides new insights into fetal heart rate asymmetry, leading to a deeper understanding of fetal health during pregnancy.