Event Timer For Microcomputer Analysis Of Fetal Biophysical Parameters

Abstract

Increased attention has recently been placed upon the study of biophysical variables for the determination of fetal health. An inexpensive and versatile system is presented which enables comprehensive fetal monitoring for periods of up to 40 minutes. This system facilitates the study of relationships among the variables: fetal heart rate, fetal body movements, and fetal breathing movements. The timing system described uses a microcomputer together with a custom-built hardware interface. This system is based on measurement of interevent periods, with a sampling interval of 1 mSec. Pulse shaping prior to sampling increases the amount of information that can be stored in memory. Our preliminary results indicate that fetal body movements are associated with increased heart rate and decreased beat-to-beat variability; and that fetal breathing movements are associated with an increase in beat-to-beat variability and a small decrease in heart rate.