Cardiotocography (CTG) is normally used to monitor fetal heart rate in order to determine the metabolic resources of the fetus and avoid intrauterine asphyxia. In our case study, the woman had preterm rupture of the membranes (at 39 weeks of gestation) but showed normal values e.g. CTG and fetal water. After 26.5 h, the CTG changed to a silent, hibernated pattern with tachycardia and reduced variability. Further, the mother developed fever and chorioamnionitis was suspected. Therefore, a sub-acute caesarean section performed followed by a medical examination of the newborn which showed normal values for Apgar score and vital parameters. Our interpretation is that the fetus responded to the maternal infection by a state of hibernation, shown by a pathological monotone heart rate pattern. It is remarkable that the fetus was able to sustain a well-preserved metabolism, shown by the normal acid-base status, considering the pathological and uniform CTG.