Non-invasive fetal electrocardiography.

Abstract

The recording of a fetal electrocardiogram from abdominal surface electrodes is severely obscured by additive noise. There are several sources of interference. A two-step method was used to filter the interferences. The mother's electrocardiogram is removed first. The second stage of the filter eliminates the remaining noise by means of coherent averaging techniques. These require the detection of fetal heartbeats. A detection algorithm is suggested that shows high efficiency in this environment, where signal-to-noise ratio is extremely low.