Defining Reference Ranges for Oxygenation and Heart Rate in Extremely Preterm Infants: Insights from the COSGOD III Trial

Introduction

During the immediate transition from fetal to neonatal life, rapid physiological changes occur in cardiovascular and respiratory systems. For extremely and very preterm infants (<32 weeks’ gestation), these transitions are even more complex, yet normative reference values for vital parameters such as arterial oxygen saturation (SpO₂), heart rate (HR), and cerebral oxygenation (crSO₂) remain poorly defined. The COSGOD III trial (Cerebral regional tissue Oxygen Saturation to Guide Oxygen Delivery in Preterm Neonates During Immediate Transition After Birth) sought to address this knowledge gap.

Study Overview

This secondary analysis of the COSGOD III multicenter randomized controlled trial (NCT03166722) evaluated postnatal transition data from 207 preterm infants (<32 weeks’ gestation) with favorable outcomes (survival without cerebral injury or major inflammatory morbidity). Data were collected between 2017–2022 from 11 international centers.

• Gestational age: median 29.7 weeks (range 23.9–31.9)

• Birth weight: median 1200 g (range 378–2320)

• Mode of delivery: 85% cesarean

• Resuscitation: 91% received CPAP, 62% PPV

• Cord clamping: <30 s in 57%

SpO₂ and HR were measured by pulse oximetry/ECG, while crSO₂ was continuously monitored via near-infrared spectroscopy (NIRS). Quantile regression models were used to define 10th–90th centile charts for the first 15 minutes after birth.

Key Findings

• Dynamic evolution of oxygenation: SpO₂ and crSO₂ increased progressively during the first 15 minutes, consistent with pulmonary and cerebral transition.

• Heart rate stability: HR showed a steady rise within the first 2–3 minutes, plateauing thereafter, providing reliable centile references for clinical assessment.

• Oxygen supplementation trends: FiO₂ centiles decreased over time, reflecting gradual weaning as oxygenation stabilized.

• Data quality: Missing data were minimal (<30% early minutes), underscoring robust signal acquisition in a fragile population.

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Clinical Implications

This study provides the first centile charts for simultaneous SpO₂, HR, and crSO₂ in extremely and very preterm infants during the first 15 minutes of life. These reference ranges can guide individualized stabilization strategies, inform optimal oxygen targeting, and serve as a foundation for future NIRS-guided resuscitation algorithms. Establishing normative transition physiology in this population is a critical step toward precision medicine in neonatal resuscitation.