Abstract

Introduction Measuring foetal heart rate (FHR) is critical for assessing foetal well-being, and traditional cardiotocography (CTG), though effective, has limitations such as cost, accessibility and observer bias. Newer non-invasive foetal ECG (NIFECG) devices offer more precise, reliable metrics for FHR variability and could enable remote monitoring, potentially improving early detection of foetal complications like hypoxia and stillbirth. Methods and analysis This is a single-centre prospective cohort study taking place in a tertiary maternity unit in the UK. Women with a singleton pregnancy over 26+0 weeks will be approached for participation in the control, foetal growth restriction (FGR) or diabetic groups. The NIFECG home monitoring schedule is 60 min daily for 7 days in the control group, daily from diagnosis until delivery for the FGR group, and daily from 36 weeks until delivery in the Insulin-dependent diabetic group. Longitudinal FHR raw ECG signals will be collected from participants across different gestational age ranges. Reference standards for FHR variability using metrics such as short-term variation, phase-rectified signal averaging acceleration and deceleration capacity will be established. The study will also aim to explore differences in FHR variability in FGR cases against controls and propose safety thresholds to guide decision-making for delivery. Ethics and dissemination Approvals have been obtained from the London Stanmore Research Ethics Committee and from the Medicines and Healthcare Regulatory Agency. The results will be published in peer-reviewed journals, presented at conferences and used by the commercial sponsor to pursue European Conformity regulatory compliance marking and future clinical studies. Trial registration number NCT06497205.