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Iran Red Crescent Med J. 2015 Aug 29;17(8):e15001. doi: 10.5812/ircmj.15001. eCollection 2015 Aug.

Gastrointestinal Complications of Ferrous Sulfate in Pregnant Women: A Randomized Double-Blind Placebo-Controlled Trial.

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School of Nursing and Midwifery, Health Care Research Center, Qom University of Medical Sciences, Qom, IR Iran.
PhD Student in Medical Education, Department of Medical Education, Tehran University of Medical Sciences, Tehran, IR Iran.



Some pregnant women discontinue iron supplements consumption due to Gastrointestinal (GI) complications, whereas pregnancy induces the same complications physiologically.


The aim of the present study was to assess GI complications of ferrous sulfate in pregnant women.


This randomized, double-blind, placebo-controlled clinical trial was performed on 176 pregnant women referred to prenatal care clinic of Maryam Hospital from April 2011 to February 2012. Pregnant women with Hb ≥ 13.2 gr/dL at 13(th) - 18(th) weeks of gestation were selected based on the inclusion criteria and were randomly assigned to the ferrous sulfate and placebo groups. The ferrous sulfate group (n = 90) received a 50-mg ferrous sulfate tablet daily from the 20(th) week to the end of pregnancy and the placebo group (n = 89) received one placebo tablet in the same way. All participants were visited twice at 24(th) - 28(th) and 32(nd) - 36(th) weeks to assess the GI complications as well as Hb level to determine the Hb changes in two groups. Chi-square test, t-test and Kolmogorov-Smirnov test were used to analyze the data. P value of < 0.05 and confidence level of 95% were considered as statistically significant.


None of the GI complications were significantly different between the ferrous sulfate and placebo groups at 24(th) - 28(th) and 32(nd) - 36(th) weeks. Hemoglobin drop lower than 10.5 gr/dL at 24(th) - 28(th) weeks or lower than 11 g/dL at 32(nd) - 36(th) weeks was not observed in any cases.


It can be concluded that GI complications in pregnant women using ferrous sulfate are mostly caused by physiologic changes of pregnancy rather than ferrous sulfate; therefore, it is not reasonable to stop using ferrous sulfate due to GI complications.


Hemoglobin; Iron Supplement; Pregnant Women; Randomized Cotrolled Trial

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