CATEGORY: WOMEN’S HEALTH
Iron pills are the usual first treatment for anemia in pregnancy, and they’re famously hard on the stomach. Pooled results from 29 randomized trials now hand the alternative a strong report card. Pregnant women treated with intravenous iron needed 37% fewer blood transfusions around delivery than women taking oral iron, and they had far fewer digestive side effects along the way.1
Twenty-Nine Trials, Added Up
A team of US researchers gathered every randomized trial comparing the two approaches in pregnancy, 29 in all, covering 11,771 women. Each trial had made the treatment choice for its participants by lottery, which is what lets the results be stacked together fairly. The condition at stake is iron deficiency anemia, too little iron to build the red blood cells that carry oxygen, and it’s one of the most common complications of pregnancy. An iron infusion delivers the mineral straight into a vein in a clinic visit or a few. Pills work slowly. The gut often protests.
Higher Iron, Fewer Transfusions
By the time they arrived to deliver, women who’d received infusions carried hemoglobin levels about 0.6 g/dL higher than women on pills. The gain was largest, about 0.7 g/dL, in those who’d started out most anemic. Iron reserves, measured as ferritin, ran far higher too. The biggest result came in the delivery ward. Transfusions were 37% less common with infusions. Newborns of infusion-treated mothers carried somewhat larger iron stores of their own, while birth weight, delivery timing and cesarean rates showed no difference.
The Side-Effect Ledger Ran Backward
Stronger treatments usually cost something in tolerability. Here the ledger ran the other way. Mild side effects were 44% less frequent with infusions, a gap driven almost entirely by an 89% drop in stomach and bowel complaints. No case of anaphylaxis, a severe allergic reaction, and no death was reported in either group across all 29 trials. The authors concluded that guidelines naming pills as the default first step may be due for a fresh look.
Key Takeaways
- Across 29 randomized trials in 11,771 pregnant women, intravenous iron meant 37% fewer blood transfusions around delivery than oral iron.
- Hemoglobin at delivery averaged about 0.6 g/dL higher with infusions, and the most anemic women gained the most.
- Infusions caused fewer side effects than pills, not more, with stomach and bowel complaints down 89%.
- Babies’ size and delivery outcomes were the same either way, and no severe allergic reactions were reported in these trials.
References
- Sales SK, Rajprohat S, Simon L, et al. Intravenous vs Oral Iron for Treating Iron Deficiency Anemia in Pregnancy: A Systematic Review and Meta-Analysis. JAMA Network Open. 2026;9(9):e2630657. link