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IV Iron Superior to Oral Iron for Managing Postpartum Anemia

December 30, 2021

For women with postpartum anemia, treatment with intravenous (IV) iron was associated with higher hemoglobin concentrations at six weeks than oral iron, according to results from a meta-analysis of randomized trials comparing the two formulations. The study, which was published in the American Journal of Obstetrics & Gynecology, also suggested that women receiving oral iron had higher risks for gastrointestinal (GI) side effects.

"Global recovery from childbirth is an underexplored topic, which has huge implications for the mother, child, family unit, and society as a whole," said study author Pervez Sultan, MD, of the University College London Hospital, when asked about the rationale for this review. "Little is known about outpatient recovery trajectories following different types of delivery and from pre-existing morbidities."

While the importance of optimizing a woman's hemoglobin level during the peripartum period has been emphasized in recent guidelines by the Society for Obstetric Anesthesia and Perinatology and the Enhanced Recovery After Surgery Society, Dr. Sultan added, postpartum anemia remains a real issue in both the developed and developing world. "If we can treat and correct this more quickly, then there is the potential for positively impacting women and their experience in their first few months of motherhood," he explained. "Currently, oral iron is used to treat iron-deficiency anemia, but approximately 40% of women are unable to tolerate this route of administration due to common GI side effects."

In this study, Dr. Sultan and colleagues performed a systematic review of 15 randomized trials that compared hemoglobin improvement between women who received oral or IV iron therapy. The pooled cohort comprised a total of 2,182 women with anemia (i.e., hemoglobin <12 g/dL), including 1,001 who received oral iron and 1,181 who received IV iron.

"[Improvement seen with IV iron is] like having a unit of blood transfused, but without the cost or potential risks."

—Pervez Sultan, MD
Among the four studies that reported on hemoglobin levels at six weeks postpartum, women in the IV iron group had hemoglobin levels that were, on average, 0.9 g/dL higher than women in the oral iron group (mean difference [MD] = 0.9 g/dL; 95% CI 0.4-1.3; p=0.0003). Compared with women who received oral iron, those who received IV iron also had higher hemoglobin concentrations immediately postpartum:
  • week 1: MD = 1.0 (95% CI 0.5-1.5; p<0.0001)
  • week 2: MD = 1.2 (95% CI 0.5-1.9; p=0.0007)
  • week 3: MD = 1.3 (95% CI 0.06-2.6; p=0.04)
In addition, women who received IV iron had higher ferritin concentrations:
  • week 1: MD = 181.47 (95% CI 163.94-198.99; p<0.00001)
  • week 2: MD = 201.82 (95% CI 148.89-254.75; p<0.00001)
  • week 4: MD = 136.32 (95% CI 44.71-227.92; p=0.004)
  • week 6: MD = 31.60 (95% CI 29.56-33.63; p<0.00001)

According to the pooled analysis, women treated with IV iron were also less likely to experience constipation (odds ratio [OR] = 0.08; p<0.001) and dyspepsia (OR=0.07; p=0.004).

Putting these results into context, Dr. Sultan said that the hemoglobin improvement seen with IV iron is "like having a unit of blood transfused, but without the cost or potential risks associated with transfusions. At a time when mothers are fatigued while looking after a new baby, the clinical effects of this higher hemoglobin level are likely to be beneficial for the mother and the child."

Although Dr. Sultan noted that IV therapy is associated with additional costs up front (including administration in a hospital environment), the "potential for reduction in blood transfusion requirement and potential reduced morbidity, together with a more favorable side-effect profile, may make this a more attractive option for women with postpartum anemia."

Limitations of the meta-analysis included the variability among the studies regarding iron delivery mode, drug regimens, and drug preparations. "We really need a large study exploring the relationship of hemoglobin recovery related to the ability to look after the baby, cognition, decision-making, and fatigue and depression," Dr. Sultan said. He added that future research should explore which hemoglobin and ferritin levels warrant iron replacement therapy in the postpartum setting.

"Current guidelines recommend the use of IV iron therapy if oral therapy fails," Dr. Sultan stated. "Perhaps it is time to have the conversation about whether we should use IV iron as a primary treatment for iron-deficiency anemia."

The authors report no conflicts of interest.


Sultan P, Bampoe S, Shah R, et al. Oral vs intravenous iron therapy for postpartum anemia: a systematic review and meta-analysis. Am J Obstet Gynecol. 2019;221:19-29.


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