Mean WISC-R IQ scores by duration of breast milk feeding after adjustment for covariates
| Measure | Duration of breast milk feeding | β Value | p Value | ||||
|---|---|---|---|---|---|---|---|
| Not breast fed | <4 months | 4–7 months | 8+ months | ||||
| Verbal IQ | 96.1 | 98.1 | 100.1 | 102.1 | 0.12 | <0.05 | |
| Performance IQ | 99.6 | 100.8 | 102.1 | 103.3 | 0.08 | >0.15 | |
WISC-R, revised Wechsler intelligence scale for children.