Table 2

Correlations between duration of breast feeding, IQ, and measures of perinatal status and family background

Measure	Duration of breast milk feeding	Verbal IQ	Performance IQ
Perinatal factors
Sex	0.06	0.05	−0.02
Multiple birth	−0.09	0.11	0.12
Birth weight	−0.06	−0.06	0.16^2-160
Gestation	−0.00	−0.01	0.08
IUGR	0.11	0.05	−0.03
Apgar score (5 min)	0.01	0.07	0.17^2-160
Social/family factors
Maternal age	−0.02	0.06	0.00
Maternal education	0.23^2-165	0.39^2-165	0.20^2-165
Family type	0.14^2-150	0.08	0.01
Family income	0.16^2-160	0.25^2-165	0.14^2-150
Maternal smoking during pregnancy	−0.16^2-160	−0.14^2-150	−0.10
Child ethnicity	−0.15^2-160	−0.35^2-165	−0.16^2-160
Birth order	−0.05	−0.04	−0.01