Efficacy and tolerability of low-dose iron supplements during pregnancy: a randomized controlled trial.
What this study found
Low-dose iron supplementation was effective and well tolerated. At the end of pregnancy, iron-deficiency anemia was lower in the iron group than in placebo, 6/198 (3%) versus 20/185 (11%), RR 0.28; 95% CI 0.12, 0.68, and iron deficiency was also lower, 65/186 (35%) versus 102/176 (58%), RR 0.60; 95% CI 0.48, 0.76. Hemoglobin and ferritin were higher with iron at delivery, with no significant worsening of gastrointestinal symptoms, serum zinc, SF-36 health concepts, or infant birth outcomes. Benefits persisted postpartum for iron deficiency, with 31/190 versus 51/177 at 6 months postpartum,…
- Study & population
- Randomized, placebo-controlled trial in pregnant women in Adelaide, South Australia, including singleton and twin pregnancies.
- Intervention
- Pregnant participants in the active arm received ferrous sulfate tablets providing 20 mg elemental iron orally once daily between meals from 20 weeks of gestation until delivery.
- Key limitation
- Some biomarker and tolerability analyses were based on subsets with missing data, which reduces precision.
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Open PDFOriginal abstract
BACKGROUND Iron deficiency anemia (IDA) is common in pregnant women, but previous trials aimed at preventing IDA used high-dose iron supplements that are known to cause gastrointestinal side effects. OBJECTIVE The objective was to assess the effect on maternal IDA and iron deficiency (ID, without anemia) of supplementing pregnant women with a low dosage (20 mg/d) of iron. Effects on iron status were assessed at the time of delivery and at 6 mo postpartum. Gastrointestinal side effects were assessed at 24 and 36 wk of gestation. DESIGN This was a randomized, double-blind, placebo-controlled trial of a 20-mg daily iron supplement (ferrous sulfate) given from 20 wk of gestation until delivery. RESULTS A total of 430 women were enrolled, and 386 (89.7%) completed the follow-up to 6 mo postpartum. At delivery, fewer women from the iron-supplemented group than from the placebo group had IDA [6/198, or 3%, compared with 20/185, or 11%; relative risk (RR): 0.28; 95% CI: 0.12, 0.68; P < 0.005], and fewer women from the iron-supplemented group had ID (65/186, or 35%, compared with 102/176, or 58%; RR: 0.60; 95% CI: 0.48, 0.76; P < 0.001). There was no significant difference in gastrointestinal side effects between groups. At 6 mo postpartum, fewer women from the iron-supplemented group had ID (31/190, or 16%, compared with 51/177, or 29%; RR: 0.57; 95% CI: 0.38, 0.84; P < 0.005). The rate of IDA between the groups did not differ significantly at 6 mo postpartum. CONCLUSION Supplementing the diet of women with 20 mg Fe/d from week 20 of pregnancy until delivery is an effective strategy for preventing IDA and ID without side effects.