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Treatments for iron-deficiency anaemia in pregnancy

  • Review
  • Intervention

Authors


Abstract

Background

Iron deficiency, the most common cause of anaemia in pregnancy worldwide, can be mild, moderate or severe. Severe anaemia can have very serious consequences for mothers and babies, but there is controversy about whether treating mild or moderate anaemia provides more benefit than harm.

Objectives

To assess the effects of different treatments for iron-deficiency anaemia in pregnancy (defined as haemoglobin less than 11 g/dl) on maternal and neonatal morbidity and mortality.

Search strategy

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (January 2007), the Cochrane Central Register of Controlled Trials (The Cochrane Library 2005, Issue 4), MEDLINE (1966 to December 2005), EMBASE (1976 to December 2005), LILACS (1982 to 40 edition), BIOSIS Previews (1980 to June 2002) and ongoing clinical trial registers. We updated the search of the Cochrane Pregnancy and Childbirth Group's Trials Register on 31 January 2010 and added the results to the awaiting classification section.

Selection criteria

Randomised controlled trials comparing treatments for iron-deficiency anaemia in pregnancy.

Data collection and analysis

We identified 17 trials, involving 2578 women. We assessed trial quality.

Main results

The trials were small and generally methodologically poor. They covered a very wide range of differing drugs, doses and routes of administration, making it difficult to pool data. Oral iron in pregnancy showed a reduction in the incidence of anaemia (one trial, 125 women; relative risk 0.38; 95% confidence interval 0.26 to 0.55). It was not possible to assess the effects of treatment by severity of anaemia. A trend was found between dose and reported adverse effects. We found that most trials had no assessments on relevant clinical outcomes and a paucity of data on adverse effects, including some that are known to be associated with iron administration. Although the intramuscular and intravenous routes produced better haematological indices in women than the oral route, no clinical outcomes were assessed and there were insufficient data on adverse effects, for example, on venous thrombosis and severe allergic reactions.

Authors' conclusions

Despite the high incidence and burden of disease associated with this condition, there is a paucity of good quality trials assessing clinical maternal and neonatal effects of iron administration in women with anaemia. Daily oral iron treatment improves haematological indices but causes frequent gastrointestinal adverse effects. Parenteral (intramuscular and intravenous) iron enhances haematological response, compared with oral iron, but there are concerns about possible important adverse effects. Large, good quality trials, assessing clinical outcomes (including adverse effects) are required.

[Note: The 23 citations in the awaiting classification section of the review may alter the conclusions of the review once assessed.]

Plain language summary

Treatments for iron-deficiency anaemia in pregnancy

Insufficient evidence to say when or how iron-deficiency anaemia in pregnancy needs to or should be treated.

Anaemia happens when the blood has insufficient red cells, or when red cells carry insufficient haemoglobin to deliver adequate oxygen to the tissues. Haemoglobin levels change in pregnancy with a normal reduction at the beginning of pregnancy and a slight rise towards the end of pregnancy. Anaemia in pregnancy can be mild, moderate or severe, and women are offered different treatments according to their level of anaemia and the possible cause. Anaemia can be caused by a range of factors including certain diseases or a shortage of iron, folic acid or vitamin B12. The most common cause of anaemia in pregnancy is due to iron shortage. Iron treatment can be given by mouth, or an injection into the muscle (intramuscular) or into the vein (intravenous), or by giving a blood transfusion. In this review we identified 17 randomised controlled trials involving over 2500 women. However, many treatment variations were studied leaving rather small study populations for each treatment and, therefore, imprecise estimates that make it difficult to draw conclusions on the effects of treatment on women with different degrees of anaemia. Amongst the complications of iron treatments, we found that intravenous treatment may cause venous thrombosis (blockages in the veins) and the intramuscular treatment caused important pain and discolouration at the injection site; but it is unclear if women and babies are healthier when women are given iron for anaemia during pregnancy. It also remains unclear what the effects of treatments given by different routes and in different populations are; therefore, it is not possible to draw a well-informed balance of benefits and harms for the differing levels of severity of anaemia. This would be better addressed if a few frequently-used treatments were compared in a multicenter randomised controlled trial involving women from different backgrounds and settings, and this study was big enough to respond to these questions in a valid way.

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