(HealthDay News) – Daily use of prenatal iron is associated with increased maternal mean hemoglobin and increased birth weight, according to research published online June 21 in BMJ.

Batool A. Haider, from the Harvard School of Public Health in Boston, and colleagues conducted a systematic review and meta-analysis to examine the correlations between maternal anemia and prenatal iron use with maternal hematological and adverse pregnancy outcomes. Data were included from 48 randomized trials (involving 17,793 women) and 44 cohort studies (including 1,851,682 women).

The researchers found that, compared with controls, prenatal iron use correlated with increased maternal mean hemoglobin concentration (4.59g/L increase) and with significant reductions in anemia, iron deficiency, iron deficiency anemia, and low birth weight (relative risks, 0.5, 0.59, 0.4, and 0.81, respectively). Iron was associated with a non-significant reduction in preterm birth. The risks of low birth weight and preterm birth were significantly increased with anemia in the first or second trimester (adjusted odds ratio, 1.29 and 1.21, respectively). Up to 66mg/day, for every 10mg increase in iron dose/day, the relative risk of maternal anemia was 0.88, birth weight increased by 15.1g, and there was a 3% decrease in the risk of low birth weight. Birth weight increased by 14g for each 1g/L increase in mean hemoglobin, although hemoglobin was not associated with low birth weight or preterm birth.

“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,” the authors write. “An improvement in prenatal mean hemoglobin concentration linearly increased birth weight.”

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