Iron deficiency in women of child bearing age

Anaemia is the most common dietary deficiency in the western world and a shortfall of iron in the diet is the main cause. The NDNS¹ found that a quarter of all women aged between 19 and 64 years had intakes of iron below the LRNI, putting them at significant risk of developing iron deficiency anaemia. Two fifths of women under the age of 34 and 53% of women receiving benefits have intakes below the LRNI. Blood samples taken during the NDNS also showed evidence of poor iron intake.

Iron status in pregnancy

Requirements for iron during pregnancy increase with each subsequent trimester. Women who enter pregnancy with low iron stores (serum ferritin <50mcg/l) are at greater risk of developing iron deficiency and aneamia during pregnancy².

During a normal pregnancy blood volume increases and haemoglobin concentrations fall. However, in a high percentage of women the fall in haemoglobin levels is greater than that regarded as safe and physiological³. Iron status during pregnancy has been widely studied in Europe, indicating iron deficiency of the order of 6-40%^4,5.

Effects of iron deficiency

Maternal iron deficiency anaemia can be harmful to both mother and infant. Perinatal mortality is higher in pregnant women who are anaemic, especially if severe. Several studies have also described a positive association between maternal haemoglobin level and birthweight, Apgar scores and placental weight⁴.

Iron deficiency anaemia has been shown to be a risk factor not only for preterm delivery but also for subsequent low birth weight^6,7. In his review⁷ of iron supplementation, Allen states that iron supplements improve iron status during pregnancy even for women who enter pregnancy with adequate stores.

Maternal iron status undoubtedly has an impact on foetal iron stores in early life, with infants born to mothers with poor iron status showing evidence of poor iron stores themselves^5,7. Prevalence and effects of iron deficiency in infants and toddlers has been assessed in numerous studies and a summary of these is given in the COMA weaning report⁸. Iron deficiency in infants and toddlers is of serious concern and is associated with developmental delay and deficits in cognitive function.

Iron supplementation

In the USA, the Centres for Disease Control and Prevention (CDC) recommend routine supplementation with iron (30mg a day) to ensure adequate iron stores during pregnancy and prevent the adverse effects associated with deficiency⁹. Furthermore CDC recognise that pre-natal iron supplementation is not associated with important health risks.

In the UK, a public health approach has been adopted. Both approaches seem to suffer from a certain lack of compliance. Currently no single approach may be universally acceptable to all clinicians and all circumstances. A supplement containing a moderate level of iron, however, might provide benefit to most of those who require supplemental iron and seems a prudent approach.

To summarise, iron deficiency continues to provide challenges for women of child bearing age. Iron needs remain high during pregnancy and many women appear to enter pregnancy with poor iron stores. Despite the potential negative consequences of iron deficiency during pregnancy, most women in the UK do not receive routine iron supplementation. It is necessary to recognise that whilst iron deficiency in pregnancy is associated with adverse effects, prenatal iron supplementation has not been linked with important health risks. A general supplement, containing a moderate level of iron, would appear to be the best approach for the majority of women to help ensure adequate iron intake during pregnancy.