Mean values (SE) for 115 ELBW children on intelligence tests at 5 years and 11 years with F and p values from repeated measures Analysis of Covariance with Bonferroni corrected post-hoc tests adjusted for sex and maternal education level
| Age test | Below average (n=20) | Average (n=59) | Above average (n=36) | F(2,110) | P value | ηp2 |
| 5 years | ||||||
| Verbal IQ | 75.8 (2.8) | 105.2 (1.6) | 120.6 (2.1) | 77.61 | <0.001 | 0.585 |
| Performance IQ | 77.4 (3.2) | 95.6 (1.8) | 109.9 (2.4) | 31.91 | <0.001 | 0.367 |
| 11 years | ||||||
| Verbal IQ | 66.4 (3.3) | 94.9 (1.9) | 115.4 (2.5) | 67.00 | <0.001 | 0.549 |
| Performance IQ | 57.1 (3.6) | 82.6 (2.1) | 108.8 (2.7) | 66.26 | <0.001 | 0.546 |
ELBW, extremely low birthweight.