Table 4. Variance explained (R ²) by models of predictors.

Statistical model	R 2
	FSIQ	VIQ	PIQ
Study variables (child’s age and tester)+sex	0.07	0.03	0.09
Study variables+core predictors (parental education, maternal IQ)+sex	0.24	0.20	0.20
Parental characteristics
Maternal age, paternal age, parity, maternal pre-pregnancy BMI, maternal prenatal marital status*	0.24	0.21	0.20
Pregnancy and birth
Gestational age, birth weight, Apgar score at 5 min., maternal smoking, maternal alcohol consumption*	0.25	0.20	0.21
Postnatal influences
Maternal marital status, breastfeeding, parental smoking, daycare 8+ hrs/day before age 3, separation from parents for 14+ days,irregular breakfast, maternal depression, high parental alcohol intake (>14 drinks/week (women) or >21 drinks/week (men)*	0.26	0.21	0.22
Postnatal growth
Head circumference, height, and BMI at 5 years*	0.27	0.22	0.22
Final model
Maternal age, paternal age, parity, maternal prenatal marital status, birth weight, breastfeeding, irregular breakfast,head circumference and height at 5 years*	0.29	0.25	0.24

^*Plus study variables, core predictors, and sex.