Effect of oxytocin injection on fetal heart rate based on multifractal analysis

Background: Oxytocin is a short acting drug, which needs continuous intravenous drip to maintain the effect of uterine contraction. Excessive uterine contraction may lead to abnormal blood supply of fetal placenta and fetal hypoxia. It is necessary to take care of the injection, and observe the fetal heart rate and uterine contraction, yet there is little research on potential effects on fetal by analyzing the electrocardiogram (ECG) signal from the perspective of nonlinear dynamic system. Aims: To explore the effectiveness of multifractal theory in analyzing the mechanism of oxytocin injection on the stability of fetal heart rate (FHR). Subjects: 20 healthy young parturient women who have normal singleton fetuses in full term pregnancy, they are numbered from 1 to 20, which cover the age from 20 to 40 years old. From standard obstetric observation, all of the maternals have no diabetes mellitus, smoking experience, hypertension, administration of cardiovascular effective drugs and cardiovascular diseases. Exclusion criteria: Fetal arrhythmia, intrauterine growth restriction, previous exposure to synthetic steroids in the utero and non-stress non-reassuring test on ECG. Method: multifractal detrended fluctuation analysis (MF-DFA). Results: The widths of ΔH(q) (0.5536 and 0.5607) and Δα (0.7074 and 0.7153) before and during oxytocin injection, respectively, indicating that the strength of the multifractality of the FHR variability signal during oxytocin injection is slightly graeter than before, but the difference is not very significant. In addition, long-range correlation and a fat-tailed distribution contribute to multifractality, which is the most important source that can be confirmed by shuffling and surrogating the FHR signals. To document the major source of multifractality, we shuffle and surrogate the series, and the results indicate that the fat-tailed distribution contributes to the multifractality of times series before and during oxytocin injection. Conclusions: Oxytocin injection may affect autonomic nervous system of fetus. With the increase of time, oxytocin intravenous infusion may increase the risk of fetal heart instability, while the effect is very little compared with that before oxytocin injection.