Modeling fetal--maternal heart-rate interaction.

The influence of maternal respiration on the occurrence of short-term fetal--maternal heart-rate coordination was examined using a model, which considers both heart-rate characteristics and effects of maternal respiratory sinus arrhythmia. Epochs of fetal--maternal heart-rate coordination were identified in model data produced at varying respiratory rates and compared with epochs found in real data acquired in mother-fetus pairs. The model results suggest that the low incidence of epochs found in the real data at low-breathing rates may be explained by heart-rate characteristics, but that the higher incidence at fast rates must be due to other factors.