This is a prospective observational study aiming to establish reference values of neurofilaments in late preterm newborns (34-37 weeks of gestation) and to evaluate their early postnatal evolution.

Neurofilaments are neuronal proteins released into the blood when nerve cells are damaged. They have emerged as promising biomarkers in neurodegenerative diseases, particularly in spinal muscular atrophy (SMA), where higher levels are associated with disease activity. However, very limited data exist on the normal dynamics of neurofilament levels in preterm infants.

In this study, up to 15 preterm newborns hospitalized in the neonatal unit will be enrolled (5 at 34 weeks, 5 at 35 weeks, 5 at 36 weeks of gestation). A maximum of 1 mL of additional blood will be collected only during routine clinically indicated blood draws, at birth, on day 2, and weekly until 37 weeks of gestation. Samples will be analyzed for neurofilament concentrations and compared across gestational ages, over time, and with existing data from term newborns and SMA patients.

The expected outcome is to generate normative data on neurofilament levels in late preterm infants, which will help interpret biomarker values in future studies and optimize early diagnosis and treatment strategies for neurodegenerative diseases such as SMA.

Recent therapeutic advances in spinal muscular atrophy (SMA) have highlighted the importance of very early treatment, ideally before the onset of symptoms. Neurofilaments, structural proteins of neurons released into the blood when axons are damaged, have been identified as sensitive biomarkers of neurodegeneration and disease activity in SMA. Elevated neurofilament levels have been reported in affected infants, with a rapid decline following initiation of effective treatment.

Despite their growing importance as a biomarker, little is known about the normal postnatal dynamics of neurofilaments in preterm infants. Establishing normative data in this population is essential to correctly interpret biomarker levels in newborn screening programs and clinical follow-up, particularly for conditions such as SMA where treatment decisions rely on early biological signals.

Inclusion Criteria:

• Gestational age between 34 and 37 weeks of amenorrhea.
• Blood test scheduled for clinical reasons.
• Signed parental consent.

Exclusion Criteria:

• Known neurological disorders.
• Severe congenital malformations.
• Medical contraindication to blood sampling.

Late preterm infants (34-37 weeks of gestation) admitted to the neonatal unit