The systematic review – led by researchers from the World Health Organisation (WHO) – investigated the benefits and harms of intermittent supplementation with iron alone supplements, both alone and in combination with folic acid or other vitamins and minerals, in pregnant women.
Juan Pablo Peña-Rosas, department of nutrition for health and development at the WHO, and his research team compiled data from more than 4,000 women in 18 different clinical studies – finding that overall taking fewer iron supplements during pregnancy works just as well for preventing anemia as taking one per day.
"Intermittent iron supplementation could be considered as a feasible alternative to daily supplementation for preventing anaemia during pregnancy, particularly in developed countries where anaemia in pregnancy is not a public health problem and there is good antenatal care for monitoring anaemia status," said Peña-Rosas.
He noted that the review also showed that women experienced fewer side effects when taking iron supplements intermittently rather than daily.
A lack of iron can lead to low levels of haemoglobin in the blood – known as anaemia. In pregnant women this can potentially increase the risk of complications at delivery.
Peña-Rosas noted that it may also be harmful to their babies, through increased risk of low birth weight and delayed growth and development later in life.
However, he added that haemoglobin levels should be carefully controlled during pregnancy, because high concentrations have also been associated with an increased risk of babies being born early or with low birth weight.
The researchers analysed data from 18 trials involving a total of 4,072 pregnant women who took iron supplements alone, with folic acid or with multi-vitamin and mineral supplements.
According to the results, women who took iron supplements once, twice or three times a week on non-consecutive days were no more likely to suffer from anaemia by the end of their pregnancies than those who took them daily.
The team also found that their babies were no more likely to be born early or have a low birth weight.
Furthermore, those taking the supplements intermittently rather than daily were less likely to experience side effects including nausea, constipation and high haemoglobin levels during pregnancy.
“Although the evidence is limited and the quality of the trials was low or very low, intermittent [supplementation] may be a feasible alternative to daily iron supplementation among those pregnant women who are not anaemic and have adequate antenatal care,” concluded the WHO reviewers.
Source: The Cochrane Library
Published online ahead of print, doi: 10.1002/14651858.CD009997
“Intermittent oral iron supplementation during pregnancy”
Authors: J. P. Peña-Rosas, L.M. De-Regil, T. Dowswell, F.E. Viteri