BackgroundTo determine the diagnostic accuracy of Hammersmith Neonatal Neurological Examination (HNNE) at 30–32 weeks postmenstrual age (PMA, ‘Early’) and term equivalent age (TEA) in infants born <31 weeks PMA to predict cognitive outcomes at 12 months corrected age (CA).MethodsProspective cohort study of 119 infants (73 males; median 28.4 weeks gestational age at birth) who underwent Early and TEA HNNE. At 12 months CA, 104 participants completed Bayley Scales of Infant and Toddler Development, 3rd Edition, (Bayley-III). Optimum cut-off points for each HNNE subscale were determined to establish diagnostic accuracy for predicting adverse cognitive outcomes on the Bayley-III Cognitive Composite Scale (≤85).ResultsThe best diagnostic accuracy for HNNE total score at 30–32 weeks PMA predicting cognitive impairment occurred at cut-off ≤16.7 (sensitivity (Se) = 71%, specificity (Sp) = 51%). The Abnormal Signs subscale demonstrated the best balance of sensitivity/specificity combination (Se = 71%, Sp = 71%; cut-off ≤1.5). For HNNE at TEA, the total score at cut-off ≤24.5 had Se = 71% and Sp = 47% for predicting cognitive impairment. The Tone Patterns subscale demonstrated the strongest diagnostic accuracy at TEA (Se = 71%, Sp = 63%; cut-off ≤3).ConclusionsEarly and TEA HNNE demonstrated moderate diagnostic accuracy for cognitive outcomes at 12-months CA in infants born <31 weeks gestational age.Clinical Trial Registration:Australian New Zealand Clinical Trials Registry; Trial Registration Number: ACTRN12613000280707; web address of trial:http://www.ANZCTR.org.au/ACTRN12613000280707.aspx.ImpactEarly Hammersmith Neonatal Neurological Examination (HNNE) assessment at 30–32 weeks postmenstrual age has moderate diagnostic accuracy for cognitive outcomes at 12 months corrected age in infants born <31 weeks gestation.Early HNNE at 30–32 weeks has stronger predictive validity than HNNE at term equivalent age.Early HNNE may provide an early marker for risk-stratification to optimise the planning of post-discharge support and follow-up services for infants born preterm.