Fig. 1. Plasma concentration ratios for phenylephrine and ephedrine. Data are shown for ( A ) umbilical venous to maternal arterial (UV/MA) and ( B ) umbilical arterial to umbilical venous (UA/UV) ratios. Box plots display the 25th, 50th, and 75th percentiles as horizontal lines on a bar, whiskers above and below the box indicate the 90th and 10th percentiles, and data beyond the 10th and 90th percentiles are displayed as individual points . Data were significantly different between groups ( P ≤ 0.001) for both concentration ratios.