Effect of iron supplementation during pregnancy on the intelligence quotient and behavior of children at 4 y of age: long-term follow-up of a randomized controlled trial

Pregnant women (n = 430) were randomly allocated to receive iron (20 mg/d) or placebo from 20 wk gestation until delivery, and the women and their children were followed up over the long term (4 y). Seventy percent of these families participated in the follow-up. The proportion of women with iron deficiency anemia at the end of pregnancy was 1% (2 of 146) in the iron group and 11% (15 of 141) in the placebo group. The mean IQ was not significantly different (P = 0.980) between the children of the iron-supplemented mothers (109 +/- 11; n = 153) and the children of the mothers in the placebo group (109 +/- 11; n = 149). However, the percentage of children with an abnormal behavior score was higher in the iron group (24 of 151, or 16%) than in the placebo group (12 of 149, or 8%); the relative risk was 1.97 (95% CI: 1.03, 3.80; P = 0.037). There was no significant difference in the health of the mothers between groups, as assessed by the SF-36 Health Survey.