Measuring fetal heart rate (FHR) through various methods is essential for assessing fetal wellbeing antenatally. This enables clinicians to identify patterns that could indicate fetal hypoxia.
Cardiotocography (CTG), which uses Doppler ultrasound, is the gold standard for non-invasive FHR monitoring. This technology detects movement in the cardiac structures and approximates the FHR from this and requires signal modulation and auto-correlation to provide accurate quality readings of FHR. This method of external FHR monitoring is prone to signal loss, maternal fetal ambiguity where the maternal heart rate is confused for FHR, and signal artefacts (e.g., double-counting, and half-counting), during both antenatal and intrapartum monitoring, and must be performed by an obstetric provider.
Non-invasive fetal electrocardiography (NIFECG) is a form of electrocardiography (ECG), which captures simultaneous maternal and fetal PQRST waves. NIFECG has the theoretical benefits of minimizing maternal-fetal heart activity confusion, is not affected by maternal adiposity, and delivers no energy to the patient, which permits prolonged periods of fetal monitoring with safety. To date, NIFECG has mostly been limited to research use due to low fetal signal-to-noise ratios. Despite technical challenges, NIFECG may be the most promising method of ambulatory self-applied FHR monitoring.
