Supplementary Material for: Fetal and Postnatal Head Circumference Growth: Synergetic Factors for Neurodevelopmental Outcome at 2 Years of Age for Preterm Infants

<i>Abstract:</i> Preterm infants present higher risk of non-optimal neurodevelopmental outcome. Fetal and postnatal growth, in particular head circumference (HC), is associated with neurodevelopmental outcome. <i>Objectives:</i> We aimed to calculate the relationship between HC at birth, HC delta Z-score (between birth and hospital discharge), and non-optimal neurodevelopmental outcome at 2 years of corrected age in preterm infants. <i>Methods:</i> Surviving infants born ≤34 weeks of gestation were included in the analysis. The relationship between the risk of being non-optimal at 2 years and both HC at birth and HC growth was assessed. The 2 Z-scores were considered first independently and then simultaneously to investigate their effect on the risk of non-optimality using a generalized additive model. <i>Results:</i> A total of 4,046 infants with both HC measures at birth and hospital discharge were included. Infants with small HC at birth (Z-score 2) while adjusting for gestational age, twin status, sex, and socioeconomic information. <i>Conclusions:</i> HC at birth and HC dZ-score between birth and hospital discharge are synergistically associated to neurodevelopmental outcome at 2 years of corrected age, in a population-based prospective cohort of preterm infants born ≤34 weeks of gestation.