Abstract: A computer-implemented method of generating data indicating tension of oxygen and/or carbon dioxide in blood of a preterm baby based upon data indicating brain activity of said preterm baby, the method comprising receiving said data indicating brain electrical activity of said preterm baby; processing said data indicating brain electrical activity of said preterm baby to generate activity data indicating length of at least one period of relatively low brain activity; processing said data indicating brain electrical activity of said preterm baby to generate power data indicating power of a frequency band of said data indicating brain activity of said preterm baby; and combining said activity data and said power data to generate said data predicting the tension of oxygen and/or carbon dioxide in the blood of said preterm baby.