TABLE 2.

Behavior rating scale factors in 10-y-old children who were or were not administered supplemental iron in infancy¹

Factor	Iron-supplemented (n = 659)	No added iron (n = 363)	P	Significant covariates
Motivation and response to reward
Unadjusted	11.3 ± 0.1	12.3 ± 0.2	<0.001
Adjusted	11.2 ± 0.1	12.5 ± 0.2	<0.001	Gender, maternal IQ
Externalizing behavior
Unadjusted	9.6 ± 0.2	10.2 ± 0.2	0.04
Adjusted	9.6 ± 0.2	10.1 ± 0.2	0.07	Gender
Language
Unadjusted	5.8 ± 0.1	6.3 ± 0.2	0.01
Adjusted	5.7 ± 0.1	6.4 ± 0.2	0.001	Age at testing, gender, maternal IQ
Performance concern
Unadjusted	1.3 ± 0.1	1.6 ± 0.2	0.24
Adjusted	1.3 ± 0.1	1.6 ± 0.2	0.24
Work habits and motor control
Unadjusted	8.3 ± 0.1	8.9 ± 0.2	0.002
Adjusted	8.3 ± 0.1	8.8 ± 0.2	0.03	Intensity of breastfeeding,2maternal IQ
Speed
Unadjusted	6.4 ± 0.1	6.1 ± 0.1	0.02
Adjusted	6.5 ± 0.1	6.2 ± 0.1	0.10	Gender, maternal IQ

¹Values are means ± SEs for factor scores derived from the Behavior and Attitude Checklist, completed by project psychologists. Data were missing for n = 7 and n = 3 children from the iron-supplemented and no added iron groups, respectively. IQ, intelligence quotient.

²As indexed by milliliters per day of formula or cow milk.