. 2013 Nov 13;8(11):e79200. doi: 10.1371/journal.pone.0079200

Table 2. Predictor variables and WPPSI-R scores within predictor domains, Denmark 2003–2007.

	Full scale IQ				Verbal IQ				Performance IQ
Sample mean (SD)	105.5 (12.8)				104.8 (10.7)				105.0 (16.2)
Parental characteristics^a
	β		95% CI	P	β		95% CI	p	β	95% CI	p
Parental education (years)	0.9		0.4; 1.3	<0.001	1.0		0.5; 1.4	<0.001	0.8	0.2; 1.4	0.012
Maternal intelligence (IQ points)	0.3		0.2; 0.3	<0.001	0.2		0.2; 0.3	<0.001	0.3	0.2; 0.4	<0.001
Child sex^b	−3.7		−5.1; −2.1	<0.001	0.1		−1.3; 1.5	0.887	−7.4	−9.5; −5.3	<0.001
Maternal age (years)	0.0		−0.3; 0.3	0.998	0.2		0.0; 0.4	0.084	0.2	−0.6; 0.2	0.289
Paternal age (years)	−0.1		−0.3; 0.1	0.525	−0.2		−0.3; 0.0	0.051	0.0	−0.3; 0.3	0.796
Parity 0 vs 1	−0.1		−1.8; 1.7	0.938	−1.2		−2.8; 0.4	0.151	1.0	−1.4; 3.5	0.407
0 vs. 2+	−0.6		−2.7; 1.5	0.551	−2.8		−4.8; −0.8	0.029	1.5	−1.5; 4.6	0.316
Maternal BMI (kg/m²)	−0.1		−0.3; 0.0	0.131	−0.2		−0.4; 0.0	0.007	−0.1	−0.3; 0.2	0.495
Single mother, prenatally	0.8		−2.5; 4.1	0.618	4.0		0.6; 7.4	0.022	−2.3	−8.6; 4.0	0.479
Pregnancy and birth ^a
	β	95% CI		p	β		95% CI	p	β	95% CI	p
Parental education (years)	1.0	0.5; 1.4		<0.001	1.1		0.7; 1.6	<0.001	0.8	0.2; 1.4	0.014
Maternal intelligence (IQ points)	0.2	0.2; 0.3		<0.001	0.2		0.1; 0.2	<0.001	0.3	0.2; 0.4	<0.001
Child sex^b	−3.9	−5.4; −2.5		<0.001	0.0		−1.4; 1.4	0.961	−7.8	−9.9; −5.7	<0.001
Gestational age (days)	0.0	−0.1; 0.1		0.583	0.1		0.0; 0.1	0.191	0.0	−0.1; 0.1	0.901
Birth weight (units of 100 grams)	0.2	0.0; 0.3		0.025	0.0		−0.1; 0.2	0.837	0.3	0.1; 0.5	0.002
Apgar score <7	1.2	−5.2; 7.5		0.715	1.9		−9.2; 13.1	0.733	0.4	−5.1; 5.9	0.882
Smoking in pregnancy	−0.6	−2.3; 1.1		0.494	−0.2		−1.9; 1.5	0.818	−0.9	−3.4; 1.4	0.414
Alcohol consumption in pregnancy	0.1	−1.4; 1.7		0.890	0.6		−0.9; 2.0	0.437	−0.4	−2.5; 1.8	0.752
Postnatal influences ^a
	β	95% CI		p		β	95% CI	p	β	95% CI	p
Parental education	0.8	0.4; 1.3		<0.001		1.0	0.6; 1.5	<0.001	0.6	0.0; 1.2	0.056
Maternal IQ	0.2	0.2; 0.3		<0.001		0.2	0.1; 0.2	<0.001	0.3	0.2; 0.4	<0.001
Child sex	−4.0	−5.5; −2.5		<0.001		−0.2	−1.6; 1.2	0.768	−7.8	−9.9; −5.7	<0.001
Single mother	−0.7	−3.3; 1.8		0.576		−0.2	−2.5; 2.0	0.853	−1.2	−5.1; 2.6	0.526
Breastfeeding >1 month	3.9	1.2; 6.3		0.004		3.2	0.9; 5.4	0.005	4.5	0.8; 7.9	0.016
Parental smoking	−0.6	−2.3; 1.0		0.443		−0.5	−2.1; 1.0	0.482	−0.7	−3.0; 1.6	0.544
Daycare 8+ hours/day before age 3	−0.1	−2.4; 2.1		0.904		−1.0	−3.1; 1.2	0.385	0.6	−2.5; 3.9	0.677
14+ days’ separation from parents	1.7	−3.0; 6.5		0.475		0.5	−3.7; 4.7	0.812	2.9	−3.7; 9.6	0.386
Irregular breakfast meals	−3.8	−8.3; 0.7		0.099		−2.2	−5.8; 1.3	0.218	−5.3	−11.8; 1.1	0.104
Maternal depression	0.3	−1.4; 2.0		0.725		0.4	−1.3; 2.1	0.624	0.2	−2.3; 2.7	0.877
High maternal alcohol consumption	3.6	−4.7; 12.0		0.393		0.4	−6.2; 7.1	0.895	6.8	−4.8; 18.5	0.251
High paternal alcohol consumption	−0.7	−3.8; 2.5		0.682		1.3	−2.3; 4.8	0.487	−2.6	−7.2; 2.0	0.272
Postnatal growth ^a
	β	95% CI		p		β	95% CI	p	β	95% CI	p
Parental education (years)	0.9	0.5; 1.3		<0.001		1.1	0.7; 1.6	<0.001	0.7	0.1; 1.3	0.025
Maternal intelligence (IQ points)	0.2	0.2; 0.3		<0.001		0.2	0.1; 0.3	<0.001	0.3	0.2; 0.4	<0.001
Child sex	−4.8	−6.3; −3.3		<0.001		−0.6	−2.0; 0.8	0.398	−9.0	−11.1; −6.9	<0.000
Head circumference (cm)	0.8	0.2; 1.3		0.010		0.3	−0.3; 0.8	0.354	1.3	0.4; 2.1	0.002
Head circumference squared	−0.3	−0.6; 0.0		0.045		−0.2	−0.4; 0.1	0.268	−0.4	−0.8; −0.1	0.018
Height (cm)	0.3	0.1; 0.4		0.008		0.3	0.1; 0.4	0.001	0.2	0.0; 0.5	0.082
Height squared	0.0	0.0; 0.0		0.173		0.0	0.0; 0.0	0.058	0.0	0.0; 0.0	0.508
BMI (kg/m²)	0.1	−0.6; 0.7		0.818		0.2	−0.5; 0.8	0.600	0.0	−1.0; 1.0	0.987
BMI squared	−0.2	−0.5; 0.0		0.095		−0.2	−0.4; 0.1	0.174	−0.2	−0.6; 0.1	0.137

WPPSI-R: Wechsler Preschool and Primary Scale of Intelligence-Revised.

Regression coefficients and p-values adjusted for child age, sex, and tester.

Reference category: females.