Table 2

Perinatal data and 8-year characteristics of the cohorts with utility data at 8 years of age

Era of birth
1991–9219972005
EPControlEPControlEPControl
Utility data available—n196214135169144187
Perinatal data
 Antenatal corticosteroids141 (72%)1 (0.5%)121 (90%)2 (1.2%)124 (86%)1 (0.5%)
 Multiple birth67 (34%)2 (0.9%)25 (19%)1 (0.6%)35 (24%)0 (0%)
 Caesarean birth50 (26%)25 (12%)74 (55%)46 (27%)82 (57%)55 (29%)
 Birth weight (g)892 (173)3422 (439)825 (180)3504 (455)869 (193)3592 (484)
 Gestational age (weeks)25.8 (1.1)39.4 (1.3)25.6 (1.2)39.3 (1.1)25.8 (1.2)39.5 (1.3)
 Male100 (51%)99 (46%)73 (54%)91 (54%)69 (48%)84 (45%)
 Birth weight z-score−0.23 (0.87)−0.02 (0.89)−0.52 (0.86)0.16 (0.90)−0.29 (0.85)0.27 (0.91)
 Oxygen dependence at 36 weeks90 (46%)NA54 (40%)NA83 (58%)NA
 Postnatal corticosteroids80 (41%)NA66 (44%)NA31 (22%)NA
 Grade 3 or 4 intraventricular haemorrhage17 (9%)NA5 (4%)NA11 (8%)NA
 Cystic periventricular leukomalacia13 (7%)NA5 (4%)NA4 (3%)NA
 Surgery during the primary hospitalisation54 (28%)NA40 (30%)NA44 (31%)NA
8-year data
 Corrected age assessed (years)8.7 (0.3)8.9 (0.4)8.5 (0.4)8.5 (0.3)7.7 (0.4)7.7 (0.5)
 IQ <−2 SD27/195 (14%)6/208 (3%)11/133 (8%)2/167 (1.2%)18/143 (13%)0/186 (0%)
 Cerebral palsy25 (13%)1/212 (0.5%)14/133 (11%)0/168 (0%)18/143 (13%)0 (0%)
 Blind2 (1.0%)0/212 (0%)2 (1.5%)0 (0%)0/141 (0%)0/186 (0%)
 Deaf3 (1.5%)0/212 (0%)2 (1.5%)0 (0%)5/143 (3.5%)1/185 (0.5%)
 Lower maternal education98/194 (51%)78/212 (37%)69 (51%)49/168 (29%)63/143 (44%)39/186 (21%)
 Lower social class65/194 (34%)41 (19%)35 (28%)26/161 (16%)50 (35%)20 (11%)
  • Data are n (%), or mean (SD).

  • EP, extremely preterm; NA, not available.