Daily iron supplement during pregnancy improves birthweight

Women who take a daily iron supplement during pregnancy have babies with improved birthweight and are at lower risk of having a low-birthweight baby, research has shown. The analysis1, published today on bmj.com, found that supplements of up to 66mg a day could be beneficial.

UK and US researchers analysed more than 90 published randomised trials and cohort studies that had examined prenatal iron supplementation, prenatal anaemia and birthweight in a total of almost two million women.

They found that women who took iron supplements had higher mean haemoglobin levels and a significantly lower risk of anaemia than controls – although they were not at lower risk of preterm birth. Analysing the cohort studies, they found a significantly higher risk of low birthweight and preterm birth in women who had anaemia in the first or second trimester.

There was a dose-response relationship between iron dose and outcomes – for every 10mg increase in daily iron dose, up to 66mg, there was a 12% reduction in risk of maternal anaemia, 3% reduction in risk of low birth weight, and a 15g increase in birth weight.

The authors concluded: “Our findings suggest that use of iron in women during pregnancy may be used as a preventive strategy to improve maternal haematological status and birth weight.”  They call for more research into the effectiveness and feasibility of strategies for iron delivery, including fortification and dietary diversification, particularly in ‘high burden countries’.

Meanwhile, a study2 conducted in rural Vietnam and published this week in PLoS Medicine found that twice-weekly iron-folic acid (IFA) supplementation for pregnant women was as effective as daily IFA supplementation, in terms of birth weight and infant growth. Women were significantly more likely to adhere to a twice-weekly than to a daily regimen, too.

Babies of mothers who had taken IFA twice weekly had higher cognitive scores at 6 months old than babies of mothers in the daily supplement group.

The researchers, led from Melbourne, Australia, said their research “provides additional support for the use of intermittent, rather than daily, antenatal IFA in populations with low rates of iron deficiency”.

On Medica