Developmental Trajectories of Very Preterm Infants and Implications for Routine Neurodevelopmental Follow‐Up

ABSTRACT Aim We aimed to assess a longitudinal trajectory of very preterm infants from corrected 1–5 years and examined how well performances on the Bayley Scales of Infant and (Toddler) Development (BSI(T)D) at 1 and 2 years predict cognitive outcome at preschool age. Methods From 2011 to 2018, 499 very preterm infants admitted to the Medical University of Innsbruck were assessed. Cognitive outcomes at 1 and 2 years were measured with BSID‐II/BSITD‐III, and at 5 years, full scale intelligence quotient (IQ) was evaluated. Results Of the 499 infants, 345 (69.1%) completed assessments at all three time points. Most had normal cognitive outcomes: 92.2% at 1 year, 80.3% at 2 years and 80.9% at 5 years. The 2‐year assessment demonstrated a stronger predictive value than the 1‐year assessment, both for identifying cognitive delay at 5 years (< 85 points; AUC 0.88 vs. 0.77) and for predicting full‐scale IQ scores in linear regression models ( R 2 = 46% vs. 36%). Conclusion The 1‐year assessment had limited predictive value, whereas the 2‐year assessment more effectively predicted preschool cognitive outcomes. A combination of BSITD at 1 and 2 years gave the best prediction at preschool age.