Multifractal analysis of fetal heart rate variability in fetuses with and without severe acidosis during labor

We performed multifractal analysis of fetal heart rate (FHR) variability in fetuses with and without acidosis during labor. Multifractal analysis was performed on fetal electrocardiograms in 10-minute sliding windows within the last 2 hours before delivery in 45 term fetuses divided in three groups according to umbilical arterial pH and FHR pattern: group A had pH ≥7.30 and normal FHR, group B had pH ≥7.30 and intermediate or abnormal FHR, and group C had acidosis (pH ≤7.05) and intermediate or abnormal FHR. Six multifractal parameters were compared using Wilcoxon rank sum test. Multifractal parameters were significantly different between the three groups in the last 10 minutes before delivery (P <0.05). Two parameters (H(min), zeta(2)) exhibited a significant difference 70 minutes before delivery, and one parameter (C(2)) was different 10 minutes before birth (P <0.05). Multifractal parameters were significantly different in acidotic and nonacidotic fetuses, independently from FHR pattern.