SPECTRAL-ANALYSIS OF FETAL HEART-RATE IN FLAT RECORDINGS

Flat heart rate recordings may be observed in different fetal states s uch as chronic distress and sleep, Their visual analysis do not allow the distinction between these two states. We used spectral analysis to study the heart rate patterns in 25 fetuses. Two significant (P < 5 x 10(-5)) groups were apparent from the determination of the position o f the maximum energy peak (PMEP) in the high-frequency band (0.20-0.50 Hz): a PMEP at about 0.20 Hz (group 1), and another around 0.30 Hz (g roup 2). The two groups did not differ in spectral density (SD), The o utcome of neonates showed that group 1 fetuses made good progress and produced healthy neonates; whereas group 2 comprised cases of chronic fetal distress, or even death in utero, and neonatal distress, The sig nificance of this difference in PMEP between fetal heart rate patterns in chronic distress and sleep is unclear, Studies combining the asses sment of fetal movements and the determination of PMEP are planned.