Introduction: Concentration of fetal hemoglobin (HbFc) in human neonates determines oxygen-carrying capacity of blood and the position of oxyhemoglobin dissociation curve. Near-infrared spectroscopy enables the measurement of regional cerebral tissue oxygen saturation (rScO₂) and in combination with measurements of pulsatile arterial oxygen saturation (SpO₂), the calculation of cerebral fractional tissue oxygen extraction (cFTOE). Methods: We aimed to investigate the impact of HbFc on rScO₂, cFTOE, and SpO₂ in preterm and term neonates during the first 15 min after birth. Blood analyses provided total blood hemoglobin (Hb) and HbFc measurements. Correlations between HbFc, Hb and rScO₂, cFTOE, and SpO₂ in each minute were analyzed. Results: Ninety term and 19 preterm neonates without medical support were included. HbFc was significantly higher in preterm neonates, whereas there were no significant differences in Hb between the groups. In preterm neonates, we found positive correlations of both HbFc and Hb with rScO₂ and negative correlations of HbFc and Hb with cFTOE in the first minutes after birth. In contrast, there were no significant correlations between the same parameters in term neonates. Correlations between HbFc or Hb and SpO₂ were either insignificant, negligible, or very low in both groups. Discussion/Conclusion: In preterm neonates, higher HbFc was associated with higher rScO₂ and lower cFTOE in the first minutes after birth. This phenomenon could not be confirmed in term neonates and might reflect immature autoregulation of oxygen delivery to the brain or lower oxygen consumption in preterm neonates in the first minutes of immediate postnatal transition.

Background: Conjugated hyperbilirubinemia in early infancy is a critical indicator of hepatobiliary dysfunction. Prompt and accurate identification is essential to diagnose cholestatic liver disease (CLD), particularly biliary atresia. Current guidelines define conjugated bilirubin (CB) ≥ 1 mg/dL as abnormal, irrespective of total bilirubin (TB). This study aimed to evaluate whether combining absolute and relative CB thresholds improves diagnostic performance for CLD. Methods: We retrospectively analyzed all infants aged ≤6 months of chronological age with CB ≥ 1 mg/dL admitted to the Department of Pediatrics and Adolescent Medicine, Medical University of Graz, Austria, between January 2004 and February 2025. During that period, 116,104 infants were born at our hospital catchment area; 3119 of these underwent bilirubin fractionation, and 257 infants (0.2% of total births) had a CB ≥ 1 mg/dL and were included in the analysis. Clinical and biochemical data were extracted. Diagnostic performance of the absolute (CB ≥ 1 mg/dL) and in combination with the relative (CB ≥ 20% of TB) thresholds was assessed using receiver operating characteristic (ROC) analysis for the detection of CLD. Results: Among 257 infants, 47 (18%) were diagnosed with CLD. The median age at the time of blood sampling was 18 days (IQR 9–31). The combined criterion (CB ≥ 1 mg/dL and ≥20% of TB) achieved 100% sensitivity and 61.2% specificity (AUC = 0.82, 95% CI 0.79–0.92; p < 0.001). Implementation of the combined cut-off reduced the number needed to screen from 5.5 to 2.7, representing nearly a twofold improvement in diagnostic efficiency. Conclusions: Applying both absolute (≥1 mg/dL) and relative (≥20% of total bilirubin) CB thresholds substantially improves detection of neonatal CLD in early infancy. This combined approach maintains full sensitivity while reducing false positives and unnecessary investigations, thereby enhancing diagnostic efficiency in early infancy.

Objective: The fetal-to-neonatal transition is marked by profound cardio-respiratory changes. Infections emerging within the first 48 h after birth may influence early cardiovascular adaptation. We aimed to evaluate the association between early infection/inflammation markers and vital parameters in neonates during the first 15 min after birth. Methods: This is a secondary outcome parameter post-hoc analysis of data derived from a prospective observation study. Preterm and term neonates with cerebral oxygen saturation (crSO2) monitoring (INVOS 5100C) during the first 15 min after birth and available inflammatory markers (C-reactive protein [CRP], leukocytes, immature-to-total neutrophils ratio [IT ratio]) within 48 h after birth were included. Heart rate (HR) and arterial oxygen saturation (SpO₂) were continuously recorded during the first 15 min. Inflammatory markers obtained at 16–24 and 24–48 h after birth were correlated with crSO₂, SpO₂, and HR at minute 5, 10 and 15. Results: Sixty-eight neonates were included (median (IQR) gestational age 34.0 (32.0; 35.9) weeks, birth weight 1900 (1488; 2542) grams). CRP within the first 24 h correlated negatively with crSO₂ (r = −0.314; p = 0.011) and with SpO₂ (r = −0.393; p = 0.001) at minute 15. IT ratio within 24 h correlated negatively with crSO₂ at minute 5 (r = −0.367; p = 0.005), 10 (r = −0.273; p = 0.035), and 15 (r = −0.306; p = 0.013), and with SpO₂ at minute 5 (r = −0.327; p = 0.008). IT ratio at 24–48 h correlated negatively with crSO₂ at minute 15 (r = −0.384, p = 0.012). No significant correlations were observed with HR. Leukocytes within the first 24 h after birth correlated negatively with crSO2 at minute 5 (r = −0.265; p = 0.046). Conclusions: Early inflammatory markers, particularly CRP and the IT ratio, are associated with cerebral and systemic oxygenation during immediate postnatal transition. These findings suggest a potential association between early inflammatory activation and oxygenation dynamics; however, given the observational design and modest correlation strength, the results should be interpreted cautiously and do not allow conclusions regarding causality or underlying mechanisms.

Introduction: Physiological postnatal changes in fetal hemoglobin fraction (FHbF) may affect neonatal tissue oxygenation through shifts in the oxyhemoglobin dissociation curve. We examined cross-sectional associations between FHbF and near-infrared spectroscopy (NIRS)-derived tissue oxygenation, and longitudinal associations between within-infant changes in FHbF and cerebral tissue oxygenation (cStO2) and oxygen extraction (cFTOE) during the first 3 postnatal weeks in neonates without red blood cell transfusions. Methods: This prospective observational study included 25 preterm (median [IQR] gestational age 33.6 [1.6] weeks) and 25 term (39.9 [1.4] weeks) neonates in a tertiary-center neonatal unit. Measurements were performed at T1 (days 2–3), T2 (days 5–10), and T3 (days 12–18). cStO2 was assessed by time-resolved NIRS, peripheral tissue oxygenation by spatially resolved NIRS and peripheral fractional oxygen extraction by venous occlusion. cFTOE was calculated. Total hemoglobin (Hb) and FHbF were measured by co-oximetry. Cross-sectional associations were assessed using Spearman’s rho correlations. Longitudinal trajectories and gestational age-adjusted within-infant change-on-change associations were analyzed using linear mixed-effects models. Results: No significant cross-sectional correlations were identified between FHbF and cerebral or peripheral NIRS-derived variables at any time point. Over time, Hb and cStO2 declined, cFTOE increased, while peripheral oxygenation and extraction remained stable. Within-infant Hb changes were not associated with concurrent cerebral NIRS changes. In contrast, FHbF change was associated with change in cStO2 (T2–T1: β per 1% FHbF, −0.19; 95% CI −0.33 to −0.05) and cFTOE (β 0.22; 95% CI 0.06–0.38). Conclusion: Within-infant FHbF decline was associated with increased cStO2 and decreased cFTOE, independent of total Hb.

Background/Objectives: Peripheral(-muscle) oxygenation assessed with near-infrared spectroscopy might serve as an early marker of infection/inflammation; however, evidence of its clinical relevance is lacking so far. This study aimed to develop a peripheral(-muscle) oxygenation and perfusion score (POP-Score) using the peripheral(-muscle) tissue oxygenation index (pTOI) combined with non-invasive monitoring parameters within six hours after birth. The POP-Score was designed to explore associations with elevated C-reactive protein (CRP), as an early infection/inflammation marker, in term and late-preterm neonates. Methods: Secondary outcome parameters from a prospective observational study were analysed. Included neonates weighed ≥2000 g with respiratory distress, excluding those with umbilical artery pH < 7.20. Neonates with CRP ≥ 20 mg/L were 1:4-matched to those with CRP < 20 mg/L by gestational age (±2 weeks). For pTOI measurements, a sensor was placed for a duration of 30 s, followed by four further reapplications of the sensor, using the NIRO200NX within the first six hours after birth. The POP-Score was established using the following formula: (pTOI [%] × subcutaneous fat layer thickness [cm] × heart rate [bpm])/(arterial oxygen saturation [%] × systolic blood pressure [mmHg]). POP-Score was correlated with the highest CRP within 48 h. Results: Thirty neonates were included (median gestational age: 39.1 weeks [CRP < 20 mg/L group] vs. 37.3 weeks [CRP ≥ 20 mg/L group], p = 0.299; median birth weight: 3561 g vs. 3260 g, p = 0.058, respectively). Median POP-Scores were significantly different: 1.11 (CRP ≥ 20 mg/L) vs. 0.85 (CRP < 20 mg/L), p < 0.001. POP-Score correlated positively with CRP (r = 0.341; p = 0.070). In this small exploratory cohort, a POP-Score cut-off of 1.00 was associated with CRP ≥ 20 mg/L (100% sensitivity and 87% specificity); however, these estimates are uncertain due to the limited sample size. Conclusions: This study is the first to describe a new score for peripheral(-muscle) oxygenation and perfusion (POP-Score), which may represent a potential approach for early, non-invasive assessment but requires validation in adequately powered studies before any clinical application. Trial Registration: Clinicaltrials.gov, Trial registration number: NCT04818762, Date of Registration: 26 March 2021.