Cardiotocography (CTG) is one of the most frequently used tools for intrapartum fetal surveillance. In daily obstetric practice, however, the value of CTG depends not only on whether a tracing is technically adequate, but also on how consistently clinicians interpret the same set of fetal heart rate features. Baseline rate, variability, accelerations and decelerations can usually be described separately, yet the transition from description to a final clinical category is less straightforward. At this stage, professional experience, previous training, the classification system used and the clinician’s usual decision-making habits may all influence the conclusion. The consequence is that apparently similar tracings may prompt different levels of concern and different clinical responses.