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Pregnancy: no iron supplements if there is no anaemia

Excessive iron supplements taken by pregnant women increase the risk of premature birth, of hypotrophy of the newborn and hypertension in the mother.

During pregnancy, iron deficiency generally manifests itself as anaemia (insufficient number of red cells or haemoglobin) and is often associated with premature births and low birth weight. The best way of preventing anaemia is a balanced diet. Treatment with iron supplements should be regularly monitored to avoid iron overload.

A Prescrire review on routine iron supplementation in pregnant women who are not anaemic was mainly based on two trials. The first, including 750 women, showed a high rate of maternal arterial hypertension and a higher number of infants with a lower birth weight in the women given iron supplements. Another trial in 120 women showed a higher number of premature births and low birth weight in infants born to women presenting a high haemoglobin count. An American study revealed that women with a high level of haemoglobin during pregnancy tended to give birth to babies with a low birth weight. Overall, iron supplements should be avoided in pregnant women who are not anaemic, in other words whose haemoglobin count is over 11 g/100 ml in the first and third trimesters, and 10.5 g/100 ml in the second trimester.

©Prescrire January 2010

"Non-anaemic pregnant women should not take iron supplements" Prescrire Int 2009; 18 (104): 261 (pdf, subscribers only)

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