The aim of this study is to investigate the relationship between cerebral and peripheral oxygenation and oxygen extraction, as measured by NIRS (near-infrared spectroscopy ), and the FHbF (fraction of fetal hemoglobin) and absolute HbF (fetal hemoglobin) concentration in postnatal conditions in term and preterm neonates.

During gestation the main fetal oxygen carrier is fetal hemoglobin (HbF). HbF exhibits a significantly higher affinity for oxygen when compared to adult hemoglobin (HbA), which makes it more suitable for oxygen extraction at the lower partial oxygen pressures in utero. Although the regulation of HbF expression is determined developmentally, recent studies report a respectable variation in the fraction of HbF in neonates.

Such data suggest that the differences in HbF expression could affect end-tissue oxygenation in neonates.

The methodology for measuring oxygen saturation and extraction in cerebral and peripheral tissues of neonates using the near-infrared spectroscopy (NIRS) has been well practiced in our study group. However, the method has not yet been used to investigate whether the fraction of fetal hemoglobin (FHbF) plays a significant role in cerebral and peripheral oxygenation in neonates.

The aim of this study is to investigate the relationship between cerebral and peripheral oxygenation and oxygen extraction, as measured by NIRS, and the FHbF and absolute HbF concentration in postnatal conditions in term and preterm neonates.

Inclusion Criteria:

• Term and preterm neonates admitted to the neonatal intensive care unit (NICU)
• Decision to conduct full life support
• Written informed consent

Exclusion Criteria:

• No decision to conduct full life support
• No written informed consent
• Congenital malformations
• Family history of haemoglobinopathies (e.g. sickle cell anaemia, thalassaemia)

Preterm neonates (≤ 36+6 weeks of gestation) and term neonates (≥ 37+0 weeks of gestation) admitted to the NICU.