Children whose mothers take iron supplements while pregnant don’t have higher IQs than those whose mothers didn’t take iron pills, a study from Australia shows.

Animal studies have shown that iron deficiency in pregnancy - usually more severe than the anemia that may strike pregnant women - can cause brain damage in offspring, Dr. Maria Makrides of Women’s & Children’s Hospital in North Adelaide and colleagues write.

Doctors in many industrialized nations routinely advise pregnant women to take iron supplements, they add, but the evidence for their benefits is not clear. In fact, they note, the US Preventive Task Force has called for studies to look at whether iron supplementation does in fact have any effect on children’s development.

To investigate, Makrides and her team assigned 430 pregnant women to take 20 mg of iron daily or a placebo beginning at 20 weeks of gestation through delivery. They then evaluated the children’s behavior and intelligence at four years of age.

At the end of pregnancy, 1 percent of the women who took iron had anemia, compared to 11 percent of those who did not.

There was no difference in IQ between the iron group and the placebo group.

However, 16 percent of children whose mothers took iron had an abnormal behavior score, compared to 8 percent of children in the placebo group. This finding “needs to be interpreted with caution,” the researchers write, as it could have been due to chance rather than the effect of iron supplementation.

Accidental overdose with iron supplements is a common cause of poisoning in children, Makrides and her colleagues point out.

“From a public health perspective, the lack of apparent clinical benefit and the potential hazards associated with routine iron supplementation in pregnancy suggest that the risks may outweigh the benefits in well-nourished populations in whom the incidence of iron-deficiency anemia at the end of pregnancy is about 11 percent,” they conclude.

SOURCE: American Journal of Clinical Nutrition, May 2006.