title: Effects and safety of preventive oral iron or iron+folic acid supplementation for women during pregnancy.
abstract: BACKGROUND
  Intake of supplements containing iron or a combination of iron and folic acid by pregnant women may improve maternal health and pregnancy outcomes. Recently, intermittent supplementation regimens have been proposed as alternatives to daily regimens.
  
  
  OBJECTIVE
  To assess the effectiveness and safety of daily and intermittent use of iron or iron+folic acid supplements by pregnant women.
  
  
  METHODS
  We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (March 2009) and contacted relevant organisations for the identification of ongoing and unpublished studies.
  
  
  METHODS
  All randomised or quasi-randomised trials evaluating the effect of supplementation with iron or iron+folic acid during pregnancy.
  
  
  METHODS
  We assessed the methodological quality of trials using the standard Cochrane criteria. Two authors independently assessed which trials to include in the review and one author extracted data.
  
  
  RESULTS
  We included 49 trials, involving 23,200 pregnant women. Overall, the results showed significant heterogeneity across most prespecified outcomes and were analysed assuming random-effects. The trials provided limited information related to clinical maternal and infant outcomes.Overall, daily iron supplementation was associated with increased haemoglobin levels in maternal blood both before and after birth and reduced risk of anaemia at term. These effects did not differ significantly between women receiving intermittent or daily iron or iron+folic acid supplementation. Women who received daily prenatal iron supplementation with or without folic acid were less likely to have iron deficiency at term as defined by current cut-off values than those who received no treatment or placebo. Side effects and haemoconcentration (a haemoglobin level greater than 130 g/L) were more common among women who received daily iron or iron+folic acid supplementation than among those who received no treatment or placebo. The risk of haemoconcentration during the second and third trimester was higher among those on a daily regimen of iron supplementation. The clinical significance of haemoconcentration remains uncertain.
  
  
  CONCLUSIONS
  Universal prenatal supplementation with iron or iron+folic acid provided either daily or weekly is effective to prevent anaemia and iron deficiency at term. We found no evidence, however, of the significant reduction in substantive maternal and neonatal adverse clinical outcomes (low birthweight, delayed development, preterm birth, infection, postpartum haemorrhage). Associated side effects and particularly haemoconcentration during pregnancy may suggest the need for revising iron doses and schemes of supplementation during pregnancy and adjust preventive iron supplementation recommendations.
authors.affiliation: Reduction of Micronutrient Malnutrition Unit, Department of Nutrition for Health and Development, World Health Organization, 20 Avenue Appia, Geneva 27, Switzerland, 1211.
authors.forename: Juan Pablo
authors.initials: JP
authors.lastname: Peña-Rosas
authors.forename: Fernando E
authors.initials: FE
authors.lastname: Viteri
mesh_terms: D018798:Anemia, Iron-Deficiency / Q000517:prevention & control; D019587:Dietary Supplements / Q000009:adverse effects; D005260:Female; D005492:Folic Acid / Q000008:administration & dosage*; D006801:Humans; D007501:Iron / Q000008:administration & dosage*; D011247:Pregnancy; D011250:Pregnancy Complications, Hematologic / Q000517:prevention & control; D011256:Pregnancy Outcome; D011295:Prenatal Care / Q000379:methods; D016032:Randomized Controlled Trials as Topic
chemical_list: D005492:Folic Acid; D007501:Iron