Iron Overload Risks for Pregnant Women

A new study conducted by researchers at Children’s Hospital Oakland Research Institute (CHORI), in close collaboration with scientists at the National Institute of Perinatology in Mexico, is the first to show that the current iron supplement recommendation for pregnant women who are not anemic is too high and could lead to birth complications for infants such as premature birth and low birth weight. This new research conflicts with recommendations from the World Health Organization (WHO) and the Centers for Disease Control (CDC). It is hoped that the results of this study will lead to new recommendations from both organizations.

The study, featured in the May issue of Archives of Medical Research, suggests that pregnant women who are not anemic should take iron supplements weekly rather than daily. Women who are anemic have low levels of healthy red blood cells and need higher doses of iron supplementation. The study shows that pregnant women who are not anemic and follow the recommended daily dosage can suffer from iron overload and are more likely to experience birth complications.

Iron deficiency is common among women of childbearing age. Consequently, doctors have ordered daily supplements of 60 to 120 mg of iron to prevent or correct anemia and iron deficiency during pregnancy. “What happens is that excess iron in pregnancy can drive the hemoglobin levels above desirable levels, so that by the end of the second trimester of pregnancy, 27 percent of the non-anemic women in our study had hemoglobin levels that were undesirably high,” said Fernando Viteri, MD, Scientist at Children’s Hospital Oakland Research Institute (CHORI). “In these women, the risk of delivering premature babies or newborns with low birth weight quadrupled.”

In contrast, only 7 percent of the women on weekly supplements developed high hemoglobin levels. The reason for the weekly dose -  and in far smaller amounts -  is biological and corresponds with the turnover of the intestinal lining, which renews itself every five to six days. The fresh cells are programmed to absorb iron according to the person’s iron reserves and needs. The cells absorb more if reserves are depleted and less if they are adequate. Dr. Viteri’s research concludes that iron supplementation is still beneficial, but must be regulated based on whether a woman is anemic.

Children’s Hospital & Research Center Oakland

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Revision date: June 11, 2011
Last revised: by Andrew G. Epstein, M.D.