Quinlee was a baby born prematurely at 30 weeks of gestation because of maternal pre-eclampsia. Her birth weight was 1.5 kg. She suffered from several complications of prematurity, including respiratory distress syndrome, which required surfactant therapy and ventilatory support. She also has a patent ductus arteriosus, which closed spontaneously without any medication. She has an episode of suspected necrotising enterocolitis and has been put on parental nutrition for several weeks. Because of the prematurity, an umbilical artery catheter (UAC) and an umbilical venous catheter (UVC) were inserted for close monitoring and intravenous nutrition. She was stable initially until she was 3 weeks old; her blood pressure was noticed to be on the high side and progressively increased to a mean blood pressure of 60–85 mmHg, systolic blood pressure up to 90–120 mmHg. Because of the hypertension, her UAC was removed and replaced by a peripheral arterial line. What potential factors may have contributed to Quinlee’s elevated blood pressure?