Exploring Tortuosity as a Non-Invasive Indicator of Fetal ECG Abnormalities in Preeclamptic Pregnancies

Abstract. Preeclampsia is a major driver of perinatal morbidity in Mexico, yet no robust, non-invasive electrocardiographic biomarker reliably flags affected fe-tuses. Recently, electrocardiogram (ECG) signal tortuosity has been validated as a non-invasive biomarker capable of distinguishing between healthy and diseased adults. We investigated whether the tortuosity of the non-invasive fetal ECG (NI-FECG) differs between normotensive and pre-eclamptic pregnancies.
Five-minute epochs of NI-FECG were obtained from 26 third-trimester sin-gleton pregnancies, classified into normotensive (Control, n = 16) and preeclamptic (Preeclampsia, n = 10) groups. Recordings were acquired using six abdominal leads (C1, C3, C4, C5, C6, C7). Tortuosity was calculated using the Slope Change Code and normalized by sequence length. Comparisons were made between groups (Control vs. Preeclampsia) and across channels (C1-C7) within each group.
Tortuosity values conformed to Gaussian distributions across all leads. No intergroup differences were detected (p > 0.05). In the Control group, intrachan-nel variability was non-significant (ANOVA p = 0.1145). However, the Preeclampsia group showed a near-significant omnibus result (p = 0.0652); LSD testing revealed three significant contrasts: C3 vs C6 (p = 0.0163), C4 vs C6 (p = 0.0339) and C4 vs C7 (p = 0.0433).
Although global tortuosity failed to distinguish normotensive from preeclamptic pregnancies, channel-specific deviations confined to the preeclampsia cohort may indicate region-dependent alterations of the fetal car-diac vector. Larger, longitudinal studies employing standardized fetal lead con-figurations are warranted to determine whether spatial tortuosity patterns can evolve into a practical, low-overhead biomarker of fetal compromise.