Fig. 4. The β-endorphin, cortisol, and middle cerebral artery pulsatility index (MCA PI) responses were each significantly different between fetuses transfused at the placental cord insertion (PCI), at the intrahepatic vein (IHV) without fentanyl, and at the IHV with fentanyl, by analysis of variance. Mean values and 95% confidence intervals are shown.