Table 1

Participants recruited at birth and assessed at 8 years contrasted between eras

Characteristics1991–199219972005
Survived to 8 years, n (% live births)225 (53)151 (70)170 (63)
Fully assessed at 8 years, n (% survivors)210 (93)142 (94)147 (86)
Perinatal variables for those fully assessed
 Born outside tertiary maternity hospital, n (%)18 (9)7 (5)19 (13)
 Antenatal corticosteroids, n (%)149 (71)126 (89)125 (85)
 Multiple birth, n (%)69 (33)29 (20)35 (24)
 Cesarean delivery, n (%)56 (27)76 (54)83 (56)
 Gestational age at birth, completed weeks, mean (SD)25.8 (1.1)25.6 (1.2)25.8 (1.2)
 Birth weight, g, mean (SD)887 (175)820 (173)867 (193)
 Male, n (%)104 (50)79 (56)72 (49)
 Exogenous surfactant, n (%)88 (42)120 (85)127 (86)
 Patent ductus arteriosus, n (%)126 (60)75 (53)113 (77)
 Grade 3 or 4 intraventricular haemorrhage, n (%)17 (8)5 (4)13 (9)
 Cystic periventricular leukomalacia, n (%)14 (7)5 (4)5 (3)
 Necrotising enterocolitis, n (%)15 (7)8 (6)16 (11)
 Postnatal corticosteroids, n (%)85 (40)65 (46)32 (22)
 Oxygen requirement at 36 weeks’ postmenstrual age98 (47)59 (42)84 (57)
 Surgery during primary hospitalisation, n (%)58 (28)44 (31)46 (31)
Cognitive, academic, executive function and motor scores at age 8 years
 Fully assessed at 8 years, n (% of survivors)210 (93%)142 (94%)147 (86%)
 IQ z-score, mean (SD) N−0.70 (1.26) 210−0.80 (1.11) 142−0.74 (1.22) 147
 Reading z-score, mean (SD) N−0.39 1.11) 200−0.51 (1.13) 132−0.87 (1.14) 140
 Spelling z-score, mean (SD) N−0.34 (0.86) 199−0.51 (1.07) 133−0.87 (1.18) 138
 Arithmetic z-score, mean (SD) N−0.57 (0.96) 197−0.53 (1.17) 130−0.94 (1.26) 140
 Global Executive Composite T-score >65, n/N (%)23/184 (12)12/137 (9)40/140 (29)
 Behavioral Regulation Index T-score >65, n/N (%)23/184 (12)18/138 (13)33/140 (24)
 Metacognition Index T-score >65, n/N (%)29/184 (16)15/137 (11)40/140 (29)
 Poor motor function, n (%)*54/202 (27)32/126 (25)58/134 (43)
Social variables
 Lower maternal education, n (%)107/206 (52)71 (50)64/144 (44)
 Lower social class, n (%)69/206 (33)37/131 (28)53 (36)
  • *Either cerebral palsy or Movement ABC <5th centile or Movement ABC-2 ≤5th centile.