Transabdominal recordings of fetal heart rate in extremely small fetuses.

Introduction: As part of the fetal assessment for the Safe Passage Study, we recorded raw data of the fetal ECG via five maternal abdominal wall electrodes from 20 weeks to 23 weeks 6 days' gestation. Materials: For this study were extracted and analyzed the FHR patterns from the stored raw data in 16 stillbirths where the fetus weighed less than 1000 g and where autopsy was performed. Results: Birth weights ranged from 190 to 970 g. The proportion FHR signal loss ranged from 0.3% to 21.1%. In the smallest fetus the heart weighed 1.3 g, yet the FHR signal loss was only 0.9%.