Anaemia is a frequent condition during pregnancy, particularly among women from low- and middle-income countries who have
insufficient iron intake to meet increased iron needs. Traditionally, pregnancy anaemia has been prevented with the provision of daily
iron supplements, however, it has recently been proposed that if women take supplements less often, such as once or twice weekly
rather than daily, this might reduce side effects and increase acceptance and adherence to supplementation. In this review we assess the
benefits and harms of intermittent (i.e. two or three times a week on non-consecutive days) oral supplementation with iron or iron +
folic acid or iron + vitamins and minerals for pregnant women.
We included 27 randomised controlled trials, but only 21 trials involving 5490 women, had information on the outcomes we evaluated.
Three studies looked at intermittent iron alone versus daily iron alone, the other studies included in the review compared intermittent
iron combined with folic acid or other vitamins and minerals compared with the same supplements provided daily. Looking at all
the studies together (any intermittent regimen including iron versus a daily regimen), there was no clear evidence of differences
between groups for most of the outcomes we examined including infant birthweight, premature birth, and perinatal death, or anaemia,
haemoglobin concentration and iron deficiency in women at the end of pregnancy. However, women receiving intermittent rather than
daily iron supplements were less likely to report side effects (such as constipation and nausea). In addition, intermittent supplementation
appeared to decrease the number of women with high haemoglobin concentrations during mid and late pregnancy compared with daily
regimens. High haemoglobin concentrations may be harmful as they may be associated with an increased risk of having a premature
birth and low birthweight baby. There were no other clear differences between groups for other outcomes examined.