In this single-centre pilot study 15 preterm infants of 32 to 42 weeks gestational age will be included. Transesophageal ECG and EMG signals will be measured using an Edi-gastric tube (Maquet, Getinge Group, Solna Sweden), a CE-certified neonatal gastric tube equipped with electrodes. Due to the proximity of the esophageal electrodes within the gastric tube to the heart and diaphragm, esophageal ECG and EMG signals can be acquired and are probably less susceptible to motion artefacts of the baby than the commonly used skin electrodes. This is well known from measurements in adults. Moreover, motion of esophageal electrodes due to peristalsis, respiration and cardiac motion superimposes the ECG as baseline wander and might be a surrogate for the coordination abilities of preterm infants.