A detecting method for the fetal QRS complex with a small amplitude.

It is often impossible to determine the presence of the fetal QRS waves from leads on the maternal abdomen because the amplitude is small or noise interferes. Yet, clinically, confirmation is highly necessary. Clinicians face a great difficulty when the fetal QRS waves are not identifiable: when, for example, they are not apparent owing either to the fetal death or to the poor recording system. We therefore developed the fetal QRS complex detecting system for computer use. This system was developed through the use of two procedures. First, possible fetal QRS waves were detected by computing slopes of moving regression lines. Second, the location of the fetal QRS waves was determined from possible fetal QRS waves by using the weighted period-gram method. We recognized that this system can detect fetal QRS complex from fetal ECGs that are affected by mixture noises in the fetal ECGs accompanying both cephalic and breech presentations.