Fetal Heart Rate Variability Is Affected by Fetal Movements: A Systematic Review

Area of Science:

• Obstetrics and Gynecology
• Fetal Physiology
• Neonatal Neurology

Background:

• Fetal heart rate variability (FHRV) is crucial for assessing fetal neurological status, but conventional methods like cardiotocography (CTG) have limitations.
• Accurate beat-to-beat FHRV analysis using time and spectral domains shows promise, yet lacks standardized protocols, especially concerning fetal movements.

Approach:

• A systematic review following PRISMA guidelines was conducted, analyzing 14 observational studies from EMBASE, MEDLINE, and Cochrane Library.
• Included studies focused on fetal electrocardiography or magnetocardiography, examining the impact of fetal movements on time domain, spectral domain, and entropy analyses in healthy fetuses.

Key Points:

• All reviewed studies indicated an increase in overall FHRV during fetal movement compared to rest.
• Fetal breathing movements elevated short-term, vagal-mediated indices (RMSSD, HF) and decreased LF/HF ratio.
• Fetal body movements appeared to proportionally increase sympathetic response indicators (LF, SDNN) more than parasympathetic ones (RMSSD, HF).

Conclusions:

• Fetal movements, particularly breathing movements, demonstrably affect time and spectral domain analyses of FHRV.
• These findings underscore the necessity of accounting for fetal movements in FHRV analyses for reliable fetal surveillance.