Fig. 3. Wavelet transform analysis of blood pressure variability (BPV) before and after neuraxial blockade, averaged over 5-min periods (n = 13). Data are presented as sum of squares of coefficients of wavelet transform analysis plotted against time, before (baseline) and after (5 min, 10 min) lumbar epidural for labor pain. Levels 2, 4, and 8 reflect high-frequency power. Levels 16 and 32 reflect low-frequency power. *  P < 0.05, **  P < 0.01  versus baseline.