Pearson’s pair-wise correlation coefficients between measures of intelligence and intrauterine growth in sibling pairs (n = 235)
| PPVT-R age 5 sib 1 | PPVT-R age 5 sib 2 | Raven’s age 14 sib 1 | Raven’s age 14 sib 2 | WRAT3 age 14 sib 1 | WRAT3 age 14 sib 2 | Birth weight for sex and gestational age z score sib 1 | Birth weight for sex and gestational age z score sib 2 | |
|---|---|---|---|---|---|---|---|---|
| All p values <0.05 except those marked *p⩾0.1 and †p⩾0.05 but <0.1. PPVT-R, revised Peabody picture vocabulary test; Raven’s SPM, standard progressive matrix (a measure of general intelligence); WRAT3, wide range achievement test version 3 (reading test). | ||||||||
| PPVT-R age 5 sib 1 | 1 | |||||||
| PPVT-R age 5sib 2 | 0.52 | 1 | ||||||
| Raven’s SPM age 14 sib 1 | 0.39 | 0.16 | 1 | |||||
| Raven’s SPM age 14 sib 2 | 0.24 | 0.35 | 0.30 | 1 | ||||
| WRAT3 age 14 sib 1 | 0.31 | 0.17 | 0.35 | 0.20 | 1 | |||
| WRAT3 age 14 sib 2 | 0.13 | 0.17 | 0.11 | 0.29 | 0.38 | 1 | ||
| Birth weight for sex and gestational age z score sib 1 | 0.36 | 0.09* | 0.27 | −0.10 | 0.25 | 0.06* | 1 | |
| Birth weight for sex and gestational age z score sib 2 | 0.08* | 0.38 | 0.07* | 0.30 | 0.02* | 0.21 | 0.47 | 1 |