FRIDAY, June 21 (HealthDay News) -- Taking iron supplements during pregnancy reduces women's risk of anemia and is linked with an increase in birth weight and a reduced risk of low birth weight, a new analysis finds.

Researchers examined more than 90 studies that included a total of nearly 2 million pregnant women and found that daily iron supplements significantly reduced women's risk of anemia during pregnancy.

Anemia during the first or second trimester was associated with a significantly higher risk of low birth weight and preterm birth, according to the study, which was published online June 20 in the journal BMJ.

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In addition, the investigators found that for every 10 milligram increase in iron dose per day (up to 66 mg), mothers had a 12 percent lower risk of anemia, birth weight increased by 15 grams and the risk of low birth weight fell by 3 percent.

The World Health Organization recommends that pregnant women take 60 mg of iron per day, the study authors noted in a journal news release.

They also said iron deficiency is the most common nutritional deficiency in the world, and the most common cause of anemia during pregnancy, particularly in low- and middle-income countries. It is estimated that iron deficiency affected 32 million pregnant women worldwide in 2011.

"Our findings suggest that use of iron in women during pregnancy may be used as a preventive strategy to improve maternal [blood] status and birth weight," Batool Haider, of the departments of epidemiology and nutrition at Harvard School of Public Health in Boston, and colleagues wrote.

More information

The March of Dimes has more about anemia during pregnancy.