**Association between Regional Tissue Oxygenation and Body Temperature in Term and Preterm Infants Born by Caesarean Section**

**Marlies Bruckner 1,2, Lukas P. Mileder 1,2,\*, Alisa Richter 1, Nariae Baik-Schneditz 1,2, Bernhard Schwaberger 1,2, Corinna Binder-Heschl 1,2, Berndt Urlesberger 1,2 and Gerhard Pichler 1,2**


**\*** Correspondence: lukas.mileder@medunigraz.at; Tel.: +43-316-385-81052; Fax: +43-316-385-13953

Received: 8 September 2020; Accepted: 28 October 2020; Published: 29 October 2020

**Abstract:** Body temperature (BT) managemen<sup>t</sup> remains a challenge in neonatal intensive care, especially during resuscitation after birth. Our aim is to analyze whether there is an association between the BT and cerebral and peripheral tissue oxygen saturation (crSO2/cTOI and prSO2), arterial oxygen saturation (SpO2), and heart rate (HR). The secondary outcome parameters of five prospective observational studies are analyzed. We include preterm and term neonates born by Caesarean section who received continuous pulse oximetry and near-infrared spectroscopy monitoring during the first 15 min, and a rectal BT measurement once in minute 15 after birth. Four-hundred seventeen term and 169 preterm neonates are included. The BT did not correlate with crSO2/cTOI and SpO2. The BT correlated with the HR in all neonates (- = 0.210, *p* < 0.001) and with prSO2 only in preterm neonates (- = −0.285, *p* = 0.020). The BT was lower in preterm compared to term infants (36.7 [36.4–37.0] vs. 36.8 [36.6–37.0], *p* = 0.001) and prevalence of hypothermia was higher in preterm neonates (29.5% vs. 12.0%, *p* < 0.001). To conclude, the BT did not correlate with SpO2 and crSO2/cTOI, however, there was a weak positive correlation between the BT and the HR in the whole cohort and a weak correlation between the BT and prSO2 only in preterm infants. Preterm neonates had a statistically lower BT and su ffered significantly more often from hypothermia during postnatal transition.

**Keywords:** body temperature; hypothermia; hyperthermia; neonates; term; preterm; postnatal transition; oxygenation; tissue oxygenation; near-infrared spectroscopy
