A long-term monitoring of fetal movement at home using a newly developed sensor: An introduction of maternal micro-arousals evoked by fetal movement during maternal sleep

Abstract

Background Pregnant women's sleep disturbance due to fetal movement is well known. Fetal movement is thought to be an index of fetal well-being. However, as there has never been a way to easily and reliably record fetal movement, psychophysiological studies of pregnant women's sleep disturbance and fetal well-being have not been done. Aims To solve these methodological issues, we developed a new sensor with electrostatic capacity that can pick up acceleration of fetal movement. Methods and results Experiment I: We verified the reliability of our fetal movement recording system. Thirty-two pregnant women (from 19 to 39 weeks of gestation) were asked to lie down on a bed for about 1 h and to press a button as a subjective marker when they felt fetal movement. We simultaneously recorded maternal polysomnograms and fetal movement from the mothers' abdomens using a Medilog recorder. The mean of prevalence-adjusted bias-adjusted kappa for agreements, based on time between fetal movement signals recorded and subjective maternal markers, was substantial at 0.75. Experiment II: We recorded seven pregnant women's polysomnograms and fetal movement simultaneously during all-night sleep at home using our sensor during weeks 33 and 36 of gestation. We succeeded in recording maternal micro-arousals evoked by fetal movement. The mean value of the number of micro-arousals at 33 weeks was slightly larger than that at 36 weeks. Conclusions There was a high agreement between subjective maternal markers and fetal movement. Our recording system using the new sensor can be used for home monitoring of fetal movement.