We also know that there are longer-term effects of iron deficiency.  Horton and Ross make the estimates of the size of the cognitive effect, and its economic consequences.  See also a very interesting longitudinal study by Lozoff. E.g. B. Lozoff, E. Jimenez and J.B. Smith.  Double burden of iron deficiency in infancy and low socio-economic status.  Archives of Pediatric and Adolescent Medicine.  160(11): 1108-13, 2006.  In an RCT, infants who received iron at less than a year of age, were more alert and less anxious – and effects on their wages and employment were seen when they were followed up as young adults, in Costa Rica.