Electrohysterography during pregnancy: preliminary report

The purpose of this study was to test the ability of uterine electrical activity recorded by electrohysterography (EHG) from abdominal electrodes during pregnancy to provide reliable information about uterine contractions. In this preliminary study, abdominal EHG was used to monitor the uterine contractions of eight women, three of whom were having spontaneous contractions related to preterm labor and five of whom were having medical abortions after intrauterine fetal death. The EHG signal consisting of one electrical burst (EB) correlated with a single episode of mechanical activity (MA) in more than 66% of the recorded contractions. When mechanical or electrical activity identified as artifactual was excluded, the temporal correlation of EBs with MA was found in 89% of the recorded contractions. Furthermore, the electrical bursts detected had temporal and spectral characteristics similar to those described previously. Reliable detection of mechanical activity during early pregnancy remains problematic. Nevertheless, abdominal EHG appears suitable for noninvasive monitoring of pregnancies at risk. Further studies are needed to elucidate the significance of the EHG signal in both normal and abnormal pregnancies. It may eventually be possible to use EHG as an ambulatory monitoring tool for the early diagnosis of preterm labor.