# Antepartum Computerized Cardiotocography in High-Risk Pregnancies: Comparative Analysis of Fetal Heart Rate Parameters in Hypertensive Disorders of Pregnancy, Diabetes and Intrahepatic Cholestasis

## TL;DR

This study compares fetal heart rate patterns in high-risk pregnancies, finding that hypertensive disorders show the most concerning changes in heart rate variability.

## Contribution

The study identifies distinct fetal autonomic profiles in different high-risk pregnancy conditions using antepartum computerized cardiotocography.

## Key findings

- Short-term variability (STV) was lowest in hypertensive disorders of pregnancy (HDP), indicating impaired fetal autonomic regulation.
- Gestational diabetes mellitus (GDM) and HDP showed increased long-term variability suppression and reduced acceleration frequency.
- Intrahepatic cholestasis of pregnancy (ICP) and HDP had higher total decelerations, but severe decelerations were rare across all groups.

## Abstract

Background/Objectives: Antepartum computerized cardiotocography (cCTG) represents an essential tool for assessing fetal well-being. This study aimed to comparatively evaluate antepartum cCTG-derived indices across high-risk pregnancies to identify distinctive fetal autonomic and reactivity profiles. Methods: A comparative analysis of antepartum cCTG parameters was conducted. The cohort included pregnancies beyond 28 weeks of pregnancy, 169 cases of hypertensive disorders of pregnancy (HDP), 146 of gestational diabetes mellitus (GDM), 86 of intrahepatic cholestasis (ICP), and 87 low-risk pregnancies as controls. Results: Baseline FHR remained within the physiological range across all groups (110–160 bpm; p > 0.05). Dynamic cCTG parameters exhibited clear pathology-dependent alterations. Short-term variability (STV) showed a stepwise decline from controls to ICP and GDM, reaching its lowest values in HDP (mean 1.08 bpm; p < 0.00001), accompanied by an increased proportion of epochs with STV < 1 bpm. Long-term variability suppression (LTV < 5 bpm) was significantly higher in GDM and HDP (p = 0.0077). Acceleration frequency decreased across all pathological groups, with the most pronounced reduction observed in HDP, whereas fetal movements were paradoxically elevated in both GDM and HDP. Total decelerations were more frequent in ICP and HDP; however, repetitive, late, prolonged, and >5 min decelerations remained rare and did not differ significantly between groups. Conclusions: HDP showed the most unfavorable cCTG profiles, consistent with impaired fetal autonomic regulation and chronic subclinical hypoxemia. GDM and ICP had moderate changes, suggesting milder adaptive responses. These findings emphasize the value of quantitative cCTG in differentiating fetal autonomic patterns in high-risk pregnancies and the importance of tailored surveillance strategies.