Analyzing fetal and maternal cardiorespiratory interactions during labor

There has been very little research focused on analyzing the directed interactions between fetal and maternal heart rate and respiration during labor or otherwise. In this work we focused on a measure of information flow between the mother and fetus as a prelude to identifying features correlated with outcome. We used the PhysioNet 'Abdominal and Direct Fetal Electrocardiogram Database' representing 5-minute multichannel ECG recordings from 5 pregnant women during labor. Each recording comprised four simultaneously acquired maternal abdomen ECG leads and a fetal scalp recording. Fetal and maternal beat to beat intervals were extracted to estimate heart rate and respiration from both mother and fetus. The interactions between fetal and maternal breathing and heart rates were assessed by Neural Network-based Granger Causality (NNGC) with non-uniform embedding. For all cases the causal influence was unidirectional from respiration to heart rate for mothers and fetuses. The strongest causal link was from fetal heart period and breathing movement to maternal heart period, indicating that the maternal heart rate is mainly influenced by the fetal cardiorespiratory activity during labor. This implies that a change in the fetal breathing movement and heart rate can invoke a maternal physiological response to satisfy the fetal oxygen demand during the course of labor. Future work will focus on a larger cohort and using the information flow as a parameter to identify fetal maturity, distress and complications during labor.