Continuous Intrapartum Maternal and Fetal Temperature Monitoring

Sammanfattning: The maternal temperature is normally increasing during delivery. Maternal fever in labor is a common problem.Such fever could represent a chorioamnionitis (CAM), leading to an increased risk of neonatal encephalopathy andsubsequent cerebral palsy, as well as other complications. There are also noninfectious reasons for elevatedtemperature during delivery. There is no fetal heart rate that is specific for incipient or manifest CAM. Maternalfever in labor increases the risk of cesarean section and assisted vaginal delivery.The fetal intrapartum temperature has been studied sparsely before. Fetal head heat flux has been found to berelated to the metabolic condition of the fetus. Fetal skin temperature has been found to correlate with changingtemperature and baseline fetal heart rate.The aim of the present thesis was to investigate the fetal scalp temperature (FST) and maternal axillarytemperature (MAT) during vaginal delivery relative to progression of labor, uterine contractions, epidural analgesia(EDA), and to construct normal temperature reference ranges related to stage of labor. The purpose was also tostudy FST and MAT and the relation to inflammatory response in the placenta. Furthermore, the present thesisattempted to establish whether paracetamol (acetaminophen) has effect on fetal and maternal temperatures inlabor.An equipment to continuously record fetal scalp temperature during labor was developed by placing a temperaturesensor in the fetal scalp electrode aimed for fetal heart rate (FHR) monitoring. In the first study the equipment wasvalidated in a fetal lamb model, where the intracranial and subcutaneous temperatures were measured. Thesubcutaneous temperature mirrored the intracranial temperature closely, even in a situation of increasing fetalhypoxia, with the intracranial temperature being higher.In the following three studies the equipment was used in a total of 307 deliveries at Helsingborg hospital. Thematernal temperature was measured axillary. The development of FST and MAT was examined during normallabor. The temperatures increased significantly by progression of labor, and significantly more in the presence ofEDA. Reference intervals for maternal temperature were created. Changes of the FST were not seen duringuterine contractions.The relation between temperature and histological inflammatory changes was studied. There was a significantrelation between inflammatory changes in the placenta, umbilical cord and amniotic membranes, and maximumFST and MAT. Women with EDA had significantly more often inflammatory changes.Paracetamol is the only safe pharmacological choice to try to lower body temperature during delivery. The aim ofthe last study was to investigate the effect of paracetamol on maternal and fetal temperatures when given to febrileparturients. Neither maternal nor fetal temperatures decreased after paracetamol. However, paracetamol halted anincreasing trend and stabilized the fetal temperature, i.e. it has an anti-pyretic effect.