| WASI | Mean scores at 6.5 years | Cluster-adjusted mean difference (95% CI) |
| Full scale IQ | 110 v 102 | 5.9 (–1.0 to 12.8) |
| Verbal IQ | 109 v 99 | 7.5 (0.8 to 14.3) |
| Verbal subtest, vocabulary | 54 v 47 | 4.9 (0.4 to 9.3) |
| Verbal subtest, similarities | 57 v 51 | 4.6 (0.2 to 9.0) |
| Performance IQ | 109 v 105 | 2.9 (−3.3 to 9.1) |
| Performance subtest, block designs | 57 v 55 | 1.9 (−1.7 to 5.5) |
| Performance subtest, matrices | 53 v 51 | 1.8 (−1.9 to 5.5) |
*IQ, intelligence quotient; WASI, Wechsler Abbreviated Scales of Intelligence; other abbreviations defined in glossary.
*IQ, intelligence quotient; WASI, Wechsler Abbreviated Scales of Intelligence; other abbreviations defined in glossary.