[Small oscillations in fetal cardiac rhythm: a sign of well-being? A new approach to the diagnostic value of spontaneous recordings of fetal cardiac rhythm in pregnancy].

The authors suggest an indirect evaluation of the electrocortical activity of the fetus by looking at evidence of cyclical variations in fetal cardiac rhythm. These are shown up by periodic changes in the variability of the rhythm. The narrow association that has been established between small changes in episodes of cardiac rhythm and deep sleep--which is itself evidence of satisfactory cortical development--make this type of tracing, under certain conditions, an excellent sign of fetal wellbeing. This means that the value of small variabilities in fetal heart rhythm takes on greater importance as a prognostic feature.