Effect of prenatal iron on pregnancy outcomes

Iron deficiency is the most widespread nutritional deficiency in the world.

Researchers form Boston and London reviewed the evidence.

First, the details.

• 112 studies of more than 2 million women were included.
• Women from high and low-to-middle income countries were included.
• Anemia was defined differently in the studies, with definitions ranging from hemoglobin less than 100 gram/L to less than 115 g/L.
• Data were assessed using meta-analysis.

And, the results.

• Iron use had the following effects
  • Increased maternal hemoglobin concentration vs controls
  • Significantly reduced the risk of anemia, iron deficiency, iron deficiency anemia, and low birth weight
• The effect of iron on preterm birth was not significant.
• Iron with folic acid
  • A significant increase in hemoglobin concentration and reduction in risk of anemia in the third trimester or at delivery
• Anemia in the first or second trimester
  • There was a significantly higher risk of low birth weight and preterm birth.
• For every 10 mg increase in iron dose/day, up to 66 mg/day…
  • The relative risk of maternal anemia became significantly less.
  • Birth weight increased and the risk of low birth weight decreased significantly.
• Duration of use was not  associated with outcomes after adjusting for dose.
• For each 1 gram/L increase in hemoglobin, birth weight increased significantly.
  • However, hemoglobin level was not associated with the risk of low birth weight and preterm birth.
• No evidence of a significant effect on duration of gestation, small for gestational age births, and birth length was noted.

The bottom line?

The authors concluded, “Daily prenatal use of iron substantially improved birth weight in a linear dose-response fashion, probably leading to a reduction in risk of low birth weight. An improvement in prenatal mean hemoglobin concentration linearly increased birth weight.”

Others have reported an association between prenatal anemia and risk of preterm birth, according to the authors.

What’s new is that prenatal iron use is associated with a significant increase in birth weight and reduced risk of low birth weight.

Also, higher iron doses are associated with an increasing birth weight and decreasing risk of low birth weight. While increasing hemoglobin levels in the prenatal period are associated with higher birth weight.

7/13/13 16:06 JR