Researchers from the Iranian university of Tarbiat Modarres linked high doses of iron to blood pressure problems in pregnant women. The researchers gave 370 pregnant women a daily dose of 150mg of ferrous sulphate, which is equal to 30mg of Iron, while a control group of women were given a placebo without iron.

The researchers published their findings in the British Journal of Obstetrics and Gynecology. Women given the iron developed high blood pressure in comparison to the control group.

Anemic women have low counts of red blood cells so they are given iron supplements to aid in the production of red blood cells. The Iron helps to reduce anemia, which can causes low birthweight and premature births, but many women exceed the required intake of the supplement and risk other complications.

Some countries still prescribe Iron supplements to all pregnant women regardless of their need. According to the UK Food Standards Agency, the low doses of Iron found in multivitamins are not likely to have as negative an effect on pregnant women.

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