Spectral analysis as a diagnostic aid in the management of high-risk pregnancy.

Spectral analysis of the fetal heart rate and intrauterine pressure was done with data obtained during labor for 24 patients delivered of their infants in an obstetric intensive care unit. The patients were grouped according to clinical assessment of labor and neonatal outcome as normal (11), abnormal/premature (4), and prolonged labor/cesarean section (9). A comparison among groups of spectral density functions and of coherence functions and phase angles failed to reveal consistent features that could be used to distinguish between groups. However, an analysis of the variance (integrated spectrum) and the mean of the base-line component of the fetal heart rate showed that the values for the normal and abnormal/premature groups could be distinguished from the background population. It is suggested that a study of the joint statistics of the variance and the mean may lead to the development of a diagnostic aid to the early detection of incipient fetal distress.