Table 3. Selected predictor variables and WPPSI-R scores, Denmark 2003–2007.
| Full scale IQa | Verbal IQa | Performance IQa | |||||||||||
| β | 95% CI | p | Part. r 2 | β | 95% CI | p | Part. r 2 | β | 95% CI | p | Part. r 2 | ||
| Core predictors and sex | |||||||||||||
| Parental education (years) | 0.7 | 0.3; 1.1 | 0.002 | 0.0056 | 0.8 | 0.4; 1.3 | <0.001 | 0.0083 | 0.5 | −0.1; 1.2 | 0.078 | 0.0018 | |
| Maternal IQ (IQ points) | 0.3 | 0.2; 0.3 | <0.001 | 0.0461 | 0.2 | 0.2; 0.3 | <0.001 | 0.0329 | 0.3 | 0.2; 0.4 | <0.001 | 0.0345 | |
| Child’s sex | −4.9 | −6.3; −3.4 | <0.001 | 0.0233 | −0.6 | −2.0; 0.8 | 0.396 | 0.0004 | −9.1 | −11.2; −7.0 | <0.001 | 0.0385 | |
| Parental characteristics | |||||||||||||
| Maternal age (years) | 0.0 | −0.3; 0.2 | 0.743 | 0.0000 | 0.2 | −0.1; 0.4 | 0.131 | 0.0013 | −0.2 | −0.6; 0.1 | 0.168 | 0.0011 | |
| Paternal age (years) | 0.0 | −0.2; 0.1 | 0.617 | 0.0001 | −0.1 | −0.3; 0.0 | 0.080 | 0.0018 | 0.0 | −0.2; 0.3 | 0.729 | 0.0001 | |
| Parity 0 vs 1 | −0.6 | −2.4; 1.1 | 0.485 | 0.0003 | −1.5 | −3.1; 0.1 | 0.072 | 0.0019 | 0.3 | −2.2; 2.7 | 0.840 | 0.0000 | |
| 0 vs. 2+ | −1.4 | −3.5; 0.7 | 0.185 | 0.0010 | −3.3 | −5.3; −1.2 | 0.002 | 0.0055 | 0.4 | −2.6; 3.5 | 0.784 | 0.0000 | |
| Maternal BMI (kg/m2) | −0.2 | −0.4; 0.0 | 0.029 | 0.0028 | −0.2 | −0.4; −0.1 | 0.009 | 0.0039 | −0.2 | −0.4; 0.1 | 0.177 | 0.0010 | |
| Prenatal single mother | 0.3 | −3.0; 3.6 | 0.856 | 0.0000 | 3.5 | 0.0; 6.9 | 0.050 | 0.0022 | −2.8 | −9.2; 3.5 | 0.381 | 0.0004 | |
| Pregnancy and birth | |||||||||||||
| Birth weight (units of 100 grams) | 0.1 | 0.0; 0.3 | 0.048 | 0.0023 | 0.1 | −0.1; 0.2 | 0.392 | 0.0004 | 0.2 | 0.0; 0.4 | 0.022 | 0.0030 | |
| Postnatal influences | |||||||||||||
| Breastfeeding | 3.8 | 1.3; 6.4 | 0.003 | 0.0050 | 3.3 | 1.1; 5.5 | 0.004 | 0.0049 | 4.4 | 0.8; 8.0 | 0.017 | 0.0033 | |
| Irregular breakfast | −3.8 | −8.1; 0.5 | 0.086 | 0.0017 | −2.2 | −5.7; 1.2 | 0.205 | 0.0009 | −5.4 | −11.5; 0.8 | 0.088 | 0.0017 | |
| Postnatal growth | |||||||||||||
| Head circumference (cm) | 0.7 | 0.1; 1.2 | 0.017 | 0.0033 | 0.3 | −0.2; 0.8 | 0.266 | 0.0007 | 1.1 | 0.3; 1.8 | 0.009 | 0.0040 | |
| Head circumference squared | −0.3 | −0.6; 0.0 | 0.020 | 0.0031 | −0.2 | −0.4; 0.1 | 0.161 | 0.0011 | −0.4 | −0.8; −0.1 | 0.009 | 0.0039 | |
| Height (cm) | 0.2 | 0.0; 0.4 | 0.031 | 0.0027 | 0.2 | 0.1; 0.4 | 0.004 | 0.0047 | 0.2 | −0.1; 0.4 | 0.218 | 0.0009 | |
WPPSI-R: Wechsler Primary and Preschool Scale of Intelligence-Revised.
a
Regression coefficients, p-values, and squared partial correlations (r 2) for a model including all listed variables, adjusted for child age, sex, and tester.
Partial r 2 designates the fraction of the variance in IQ explained by the variable when all other variables are held constant.