Complexity analysis of the fetal heart rate for the identification of pathology in fetuses

Monitoring of fetal conditions is a very important step to assure a healthy newborn state. A special interest is reserved to Intrauterine Growth Restricted (IUGR) fetuses in the very preterm period, when the interpretation of fetal examinations is often very difficult. In order to study the fetal heart rate complexity we have introduced the Lempel-Ziv (LZ) complexity parameter as a global index estimating unpredictability level of the time series. We have compared this new parameter with other regularity estimators: Approximate Entropy and Sample Entropy. The results show that the LZ complexity is a stable parameter and its value significantly discriminates the severe IUGR (preterm delivered) from the not severe IUGR (at term delivered) and normal fetuses. The introduction of the LZ complexity parameter could improve the diagnostic ability of the fetal monitoring systems