Circulatory insulin-like growth factor-I and brain volumes in relation to neurodevelopmental outcome in very preterm infants.

Background:To evaluate the relationships between postnatal change in circulatory insulin-like growth factor I (IGF-I) concentrations, brain volumes, and developmental outcome at 2 years of age in very preterm infants.Methods:IGF-I was measured weekly and nutritional intake was calculated daily from birth until a postmenstrual age (PMA) of 35 weeks. Individual beta coefficients for IGF-I, IGF-I(B) representing rate of increase in IGF-I from birth until a PMA of 35 weeks were calculated. Brain MRI was performed at term age, with segmentation into total brain, cerebellar, gray matter and unmyelinated white matter volume (UWMV). Developmental outcome was evaluated using Bayley Scales of Infant Development-II.Results:Forty-nine infants, mean GA 26.0 weeks were evaluated at mean 24.6 months corrected age. Higher IGF-I(B), UWMV and cerebellar volume were associated with a decreased risk for a Mental Developmental Index (MDI)<85, OR(95%CI) 0.6(0.4-0.9), 0.96(0.94-0.99) and 0.78(0.6-0.96), respectively. In multivariate analysis, higher IGF-I(B) and higher UWMV combined with female gender constituted the two models with the highest predictive value for MDI>85.Conclusion:A higher rate of increase in circulating IGF-I is associated with a decreased risk for subnormal MDI at 2 years of corrected age. This relationship is in part dependent on brain volume at term age.Pediatric Research (2013); doi:10.1038/pr.2013.135.