Quantifying Phase Coupling between Fetal Heart Rate and Uterine Contractions.

Area of Science:

• Obstetrics and Gynecology
• Biomedical Engineering
• Signal Processing

Background:

• Cardiotocography (CTG) monitors fetal heart rate (FHR) and uterine contractions (UC) during labor.
• Current CTG quality assessment relies on signal loss, potentially missing non-physiological signals.
• Understanding FHR and UC coupling is crucial for accurate fetal response assessment.

Purpose of the Study:

• To investigate the coupling relationship between non-zero FHR and UC signals.
• To determine the potential of the phase coupling index (λ) as a CTG quality metric.
• To explore the association between λ and established FHR features.

Main Methods:

• Utilized a dataset of 271 CTG recordings and surrogate data.
• Quantified FHR-UC association using the phase coupling index (λ).
• Correlated λ with FHR features like deceleration depth and variability.

Main Results:

• Phase coupling index (λ) values differed significantly between real and surrogate data.
• λ showed significant associations with average deceleration depth (MADdtrd) and Hurst parameter (H).
• These findings indicate λ captures meaningful physiological dynamics.

Conclusions:

• The phase coupling index (λ) may serve as a novel quality metric for non-zero CTG data.
• λ has the potential to enhance both visual and computerized CTG analysis.
• This metric could improve the identification of high-quality CTG signals for better clinical interpretation.