Reminiscence of Fetal Monitoring
Fetal well-being was assessed by enlarging of pregnant abdomen and maternal perception of fetal movements during amenorrhea in old times. There was change to medical monitoring with stethoscopic listening to fetal heart sound after 20 weeks of pregnancy and palpating diagnosis of intrauterine fetus. Recognition of X-ray photo was rarely confirmed fetal position or fetal skeleton under concern on X-ray effect on the fetus. Fetal life was confirmed by appearance of fetal electrocardiogram on maternal limb leads with Seitengalvanometer, then changed to fetal electrocardiogram (FECG) at maternal abdominal surface using electric amplifier. Maeda reported it using handmade amplifier in 1950s. Objective fetal heart sound was also recorded using adult phonocardiographic microphone, transistor amplifier and data recording with slow speed reproduction to trace fetal phonocardiogram (FPCG). As P & T waves of FECG were masked by muscle noises, FPCG was disturbed by systolic murmur in normal pregnancy, and listening to fetal heart beats failed to detect fetal sinusoidal heart rate, the fetal monitoring was changed to fetal heart rate curve recording.