Feb. 16, 2010(Medscape)
Authors:Peña-Rosas Juan Pablo, Viteri Fernando E
Review Group;Cochrane Pregnancy and Childbirth Group
Abstract : 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.
Objectives:
To assess the effectiveness and safety of daily and intermittent use of iron or iron+folic acid supplements by pregnant women.
Search strategy:
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Group's Trials Register (March 2009) and contacted relevant organisations for the identification of ongoing and unpublished studies.
Selection criteria:
All randomised or quasi-randomised trials evaluating the effect of supplementation with iron or iron+folic acid during pregnancy.
Data collection and analysis:
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.
Main 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.
Authors' 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 reductionin 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.
Implications:Daily or intermittent supplementation with iron or with iron+folic acid by pregnant women clearly results in a substantial reduction in the prevalence of maternal anaemia at term and increased maternal Hb concentrations at term. However, the current sparse data fail to demonstrate that supplementation with iron alone or in combination with folic acid among women without anaemia or with mild or moderate anaemia by current cut-off criteria is significantly associated with any other substantial beneficial or adverse effects on maternal health, fetal health, or pregnancy outcomes. Available data also indicate that weekly supplementation is as effective as daily supplementation in preventing low haemoglobin levels associated with negative outcome consequences and that the use of either daily or weekly iron supplements (with or without folic acid) may be beneficial where iron deficiency and anaemia are prevalent pre-gestationally or in early pregnancy. Starting supplementation early in pregnancy must be stressed, together with interventions to improve pregnancy iron and folate status prior to conception. The evidence suggests that iron supplementation schemes providing more iron than women need may not be desirable, and doses and formulations that can reduce side effects should be encouraged. However, current preventive antenatal iron supplementation doses recommended for populations in developing countries, based on therapeutic doses, appear to be excessive even where moderate/mild anaemia is found. Consequently, current recommended iron and folic acid supplementation schemes during pregnancy should be reviewed to adjust iron doses to levels that are effective and safe for the mothers and newborns and that can assure compliance. Current preventive antenatal iron supplementation doses recommended for populations in developing countries appear to be excessive. Starting supplementation early in pregnancy must be stressed, together with interventions to improve pregnancy iron and folate status prior to conception. The evidence suggests that iron supplementation schemes providing more iron than women need may not be desirable, and doses and formulations that can reduce side effects should be encouraged. Intermittent supplementation with iron could be considered in anaemia prevention strategies not only prior to but also during pregnancy.
Citation : Peña-Rosas JP, Viteri FE. Effects and safety of preventive oral iron or iron+folic acid supplementation for women during pregnancy. Cochrane Database of Systematic Reviews 2009, Issue 4. Art. No.: CD004736. DOI: 10.1002/14651858.CD004736.pub3.
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