Neurodevelopment in small-for-gestational-age preterm infants: distinguishing the impact of birthweight and gestational age in a cohort study.
OBJECTIVE To compare early neurodevelopment at 12 months corrected age between preterm infants born small for gestational age (SGA) and appropriate for gestational age (AGA) and determine whether differences relate to birthweight or gestational age. STUDY DESIGN Prospective cohort of preterm infants (24-36 weeks) born April 2023-February 2024 at Mercy Hospital for Women, Melbourne. Infants were classified using the GROW customised centile calculator. Neurodevelopment was assessed at 12 months corrected age using the Bayley-4 A&NZ and PEDI. Regression and mediation analyses evaluated the effects of gestation and birthweight, adjusted for sex and socioeconomic status. RESULTS Among 143 infants (50 SGA, 93 AGA), follow-up at 12 months was 80%. Despite comparable mean Bayley-4 scores, moderate-to-severe developmental delay occurred mainly in SGA infants (5% vs 0-1%). Birthweight, rather than gestation, mediated cognitive and motor outcomes. CONCLUSION Birthweight better predicts early neurodevelopment than SGA status or gestational age.