Do side-effects reduce compliance to iron supplementation: a study of daily- and weekly-dose regimens in pregnancy

Abstract

Side-effects of iron supplementation lead to poor compliance. A weekly-dose schedule of iron supplementation rather than a daily-dose regimen has been suggested to produce fewer side-effects, thereby achieving a higher compliance. This study compared side-effects of iron supplementation and their impact on compliance among pregnant women in Bangladesh. These women were assigned to receive either weekly doses of 2x60 mg iron (one tablet each Friday morning and evening) or a daily dose of I x60 mg iron. Fifty antenatal care centres were randomly assigned to prescribe either a weekly- or a daily-supplementation regimen (86 women in each group). Side-effects were assessed by recall after one month of supplementation and used for predicting compliance in the second and third months of supplementation. Compliance was monitored using a pill bottle equipped with an electronic counting device that recorded date and time whenever the pill bottle was opened. Of five gastrointestinal side-effects (heartburn, nausea, vomiting, diarrhoea, or constipation) assessed, vomiting occurred more frequently in the weekly group (21 %) than in the daily group (11 %. p<0.05). Compliance (ratio between observed and recommended tablet intake) was significantly higher in the weekly supplementation regimen (93%) than in the daily-supplementation regimen (61 %, p<0.05). Overall, gastrointestinal side-effects were not significantly associated with compliance. However. the presence of nausea and/or vomiting reduced compliance in both regimens, but only among women from the lower socioeconomic group. In conclusion, weekly supplementation of iron in pregnancy had a higher compliance compared to daily supplementation of iron despite a higher frequency of sideeffects. The findings support the view that gastrointestinal side-effects generally have a limited influence on compliance, at least in the dose ranges studied. Efforts to further reduce side-effects of iron supplementation may not be a successful strategy for improving compliance and effectiveness of antenatal iron supplementation.