Ambulatory antenatal fetal electrocardiography in high-risk pregnancies (AMBER): protocol for a pilot prospective cohort study

INTRODUCTION: Fetal heart rate (FHR) monitoring is a vital aspect of fetal well-being assessment, and the current method of computerised cardiotocography (cCTG) is limited to the hospital setting. Non-invasive fetal ECG (NIFECG) has the ability to produce FHR patterns through R wave detection while eliminating confusion with maternal heart rate, but is presently limited to research use. Femom is a novel wireless NIFECG device that is designed to be placed without professional assistance, while connecting to mobile applications. It has the ability to achieve home FHR monitoring thereby allowing more frequent monitoring, earlier detection of deterioration, while reducing hospital attendances. This study aims to assess the feasibility, reliability, and accuracy of femom (NIFECG) by comparing its outputs to cCTG monitoring. METHODS AND ANALYSIS: This is a single-centred, prospective pilot study, taking place in a tertiary maternity unit. Women with a singleton pregnancy over 28(+0) weeks’ gestation who require antenatal cCTG monitoring for any clinical indication are eligible for recruitment. Concurrent NIFECG and cCTG monitoring will take place for up to 60 min. NIFECG signals will be postprocessed to produce FHR outputs such as baseline FHR and short-term variation (STV). Signal acceptance criteria is set as <50% of signal loss for the trace duration. Correlation, precision and accuracy studies will be performed to compare the STV and baseline FHR values produced by both devices. The impact of maternal and fetal characteristics on the effectiveness of both devices will be investigated. Other non-invasive electrophysiological assessment parameters will be assessed for its correlation with the STV, ultrasound assessments and maternal and fetal risk factors. ETHICS AND DISSEMINATION: Approval has been obtained from South-East Scotland Research Ethics Committee 02 and MHRA. The results of this study will be published in peer-reviewed journals, and presented at international conferences. TRIAL REGISTRATION NUMBER: NCT04941534.