Relation between Fetal HRV and Value of Umbilical Cord Artery pH in Labor, a Study with Entropy Measures

The relation between fetal heart rate and the value of umbilical cord artery pH is not something new for the scientific community. However, the problem has not been investigated sufficiently. One reason for that is the lack of open databases with a large number of recordings. Such a database is used here, recently publicly available, with cardiotocographic data recorded approximately two hours before delivery and until the end of the delivery. We use entropy measures to investigate how the value of umbilical cord artery pH is correlated to the variability of the fetal heart rhythm. We select different ranges of pH values and estimate the entropy of the time series for these recordings. We discuss the differences presented in the fetal heart rhythm and make conclusions about the correlation of the umbilical cord artery pH and the fetal heart rhythm, as well as the entropy as a means to express these differences.