Prenatal iron associated with fewer low birth weight deliveries

Bottom Line

Routine iron supplementation during pregnancy decreases the risk of anemia in mothers and decreases the likelihood of a low-birth-weight baby. It does not seem to affect the risk of preterm birth, small-for-gestational-age babies, or birth length. (LOE = 1a)

Reference

Haider BA, Olofin I, Wang M, et al, for the Nutrition Impact Model Study Group (anaemia). Anaemia, prenatal iron use, and risk of adverse pregnancy outcomes: systematic review and meta-analysis. BMJ 2013;346:f3443 doi 10.1136/bmj.f3443.

Study Design: Systematic review Funding: Foundation
Setting: Various (meta-analysis) Allocation: Unknown

Synopsis

These authors identified randomized and observational studies of iron use during pregnancy by searching 2 databases (but not the Cochrane Library), as well as reference lists of identified studies and review articles. They excluded articles that evaluated multiple vitamins unless the use of iron (with or without folic acid) was specifically isolated. They included observational studies that evaluated the association between baseline anemia and birth outcomes. Two reviewers independently screened articles for inclusion and extracted data. They identified 48 trials, including 17,793 women, and 44 cohort studies reporting on almost 2 million women. Overall, the results are conflicting, with much heterogeneity among the studies for many outcomes. Iron use during pregnancy lowers the rate of low birth weight by 19%. It does not, however, decrease the risk of preterm birth, small-for-gestational-age births, or birth length. The effect on maternal or neonatal mortality or birth complications could not be evaluated. Iron supplementation, as might be expected, increases maternal hemoglobin concentration and reduces the risk of anemia. It’s counterintuitive, but the effects on maternal anemia were higher in high-income countries.

Allen F. Shaughnessy, PharmD, MMedEd
Professor of Family Medicine
Tufts University
Boston, MA

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