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Should we lower the dose of iron when treating anaemia in pregnancy? A randomized dose–response trial

European Journal of Clinical Nutrition volume 63, pages 183–190 (2009)Cite this article

Abstract

Background/Objectives:

To compare the efficacy and side effects of low-dose vs high-dose iron supplements to correct anaemia in pregnancy.

Subjects/Methods:

One hundred and eighty women with anaemia (haemoglobin <110 g l−1) in mid-pregnancy. The women were randomly allocated to 20; 40 or 80 mg of iron daily for 8 weeks from mid-pregnancy.

Results:

One hundred and seventy-nine (99%) women completed the trial. At the end of treatment, there was a clear dose–response of increasing mean haemoglobin concentration with iron dose (111±13 g l−1 at 20 mg per day, 114±11 g l−1 at 40 mg per day and 119±12 g l−1 at 80 mg per day, P=0.006). However, the incidence of anaemia did not differ statistically between groups. Compared with women in the 80 mg iron group, the odds ratio of anaemia was 1.9 (95% CI: 0.8, 4.3, P=0.130) and 1.1 (95% CI: 0.5, 2.6, P=0.827), respectively, for women in the 20 mg iron group and the 40 mg iron group. The incidence of gastrointestinal side effects was significantly lower for women in the 20 mg iron group compared with women in the 80 mg iron group; the odds ratio was 0.4 (95% CI: 0.2, 0.8, P=0.014) for nausea, 0.3 (95% CI: 0.2, 0.7, P=0.005) for stomach pain and 0.4 (95% CI: 0.2, 0.9, P=0.023) for vomiting.

Conclusions:

Low-dose iron supplements may be effective at treating anaemia in pregnancy with less gastrointestinal side effects compared with high-dose supplements.

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Acknowledgements

This work was supported by funding from the Adelaide Women's & Children's Hospital Research Foundation. MM and RAG were supported by a National Health & Medical Research Council Senior Research Fellowship (ID: 298902 for MM and 250324 for RAG). The iron and placebo tablets used in the trial were manufactured and donated by Soul Pattinson Manufacturing, Kingsgrove, NSW, Australia. The funding organizations had no role in the design and conduct of the study, the analysis and interpretation of the data, or the preparation, review and approval of the manuscript. MM and RAG occasionally provide advice to manufacturers of nutritional supplements. SJZ and CAC have no known conflict of interest.

Author information

Authors and Affiliations

  1. Child Nutrition Research Centre, Flinders Medical Centre and Women's & Children's Hospital, Child Health Research Institute, North Adelaide, SA, Australia

    S J Zhou, R A Gibson & M Makrides

  2. School of Paediatrics & Reproductive Health, University of Adelaide, Adelaide, SA, Australia

    S J Zhou & M Makrides

  3. School of Agriculture, Food & Wine, University of Adelaide, Waite Campus, Urrbrae, SA, Australia

    R A Gibson

  4. Maternal Perinatal Clinical Trials Unit, School of Paediatrics & Reproductive Health, University of Adelaide, Women's & Children's Hospital, North Adelaide, SA, Australia

    C A Crowther

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  1. S J Zhou
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  2. R A Gibson
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  3. C A Crowther
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  4. M Makrides
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Corresponding author

Correspondence to M Makrides.

Additional information

Contributors: SJZ, MM and RAG designed the study in consultation with CAC. SJZ collected data, did the analysis and wrote the manuscript under the supervision of MM, RAG and CAC. All authors had a role in data interpretation and commented on drafts of the manuscript.

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Zhou, S., Gibson, R., Crowther, C. et al. Should we lower the dose of iron when treating anaemia in pregnancy? A randomized dose–response trial. Eur J Clin Nutr 63, 183–190 (2009). https://doi.org/10.1038/sj.ejcn.1602926

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