Participant characteristics of infants assessed at term-equivalent age (based on HNNE sample size)
| PT<30 (n=133) | MLPT (n=196) | Term control (n=186) | |
| Postnatal corticosteroids, n (%) | 12 (9) | 0 | 0 |
| Multiple birth, n (%) | 59 (44) | 73 (37) | 2 (1) |
| Caesarean delivery, n (%) | 75 (72) | 134 (68) | 72 (39) |
| Gestational age at birth (weeks), mean (SD) | 27.9 (1.4) | 34.4 (1.3) | 39.7 (1.2) |
| Birth weight Z-score, mean (SD) | −0.33 (1) | −0.33 (1.2) | 0.23 (0.82) |
| Male, n (%) | 54 (52) | 93 (47) | 99 (53) |
| Respiratory distress at birth, n (%) | 102 (98) | 44 (22) | 0 |
| Postmenstrual age at neurobehavioural assessment (weeks), mean (SD) | 41.5 (1.9) | 41.4 (1.1) | 41.9 (1.5) |
| Postmenstrual age at MRI (weeks), mean (SD) | 42.4 (1.5) | 41.4 (1.1) | N/A |
| Global brain abnormality score, n participants, mean score (SD) | 101, 4.30 (2.02) | 187, 1.82 (1.87) | N/A |
| Cerebral WM brain abnormality score, n participants, mean score (SD) | 101, 2.29 (1.35) | 187, 0.98 (1.17) | N/A |
| Cortical grey matter abnormality score, n participants, mean score (SD) | 102, 1.39 (1.28) | 193, 0.62 (0.78) | N/A |
| Deep nuclear grey matter abnormality score, n participants, mean score (SD) | 102, 0.11 (0.34) | 194, 0.04 (0.19) | N/A |
| Cerebellar abnormality score, n participants, mean score (SD) | 102, 0.51 (0.73) | 192, 0.19 (0.58) | N/A |
HNNE, Hammersmith Neonatal Neurological Examination; MLPT, moderate-to-late preterm; N/A. not applicable (term infants did not have an MRI for this study); PT<30, preterm born <30 weeks’ gestational age; WM, white matter.