Heart rate variability in the individual fetus

Area of Science:

• Perinatal Medicine
• Cardiovascular Physiology
• Biomedical Signal Processing

Background:

• Fetal heart rate and its variability (HRV) change throughout gestation, linked to fetal growth and neural development.
• Existing studies often analyze group data, potentially masking individual developmental trajectories.
• Investigating within-fetus HRV is crucial for a deeper understanding of fetal cardiovascular regulation.

Purpose of the Study:

• To investigate fetal heart rate variability (HRV) within individual fetuses across the second and third trimesters.
• To compare the consistency of HRV measures derived from individual fetuses versus pooled group data.
• To determine which HRV measures best reflect prenatal developmental factors.

Main Methods:

• Acquired 213 fetal magnetocardiograms (MCGs) from 11 fetuses (2nd-3rd trimesters).
• Calculated fetal RR interval time series and HRV measures: SDNN, RMSSD, ApEn, and Irrev.
• Performed regression analyses of HRV measures against gestational age and RR interval for each fetus.

Main Results:

• Fetal HRV measures generally increased with gestational age and RR interval.
• Within-fetus HRV consistency was greater than in pooled data.
• Approximate entropy (ApEn) showed the highest individual R(2) values and most consistent inter-subject courses, suggesting it better reflects developmental factors.

Conclusions:

• Individual fetal HRV analysis provides more consistent and reliable insights into cardiovascular regulation than group analysis.
• Complexity measures, particularly ApEn, are promising for reflecting prenatal developmental influences on fetal cardiovascular regulation.
• Further research into individualized fetal HRV analysis can enhance our understanding of fetal development and well-being.