Oral Versus Intravenous Iron for Anemia Diagnosed After 34 Weeks of Gestation: A Randomized Controlled Trial

Anemia during pregnancy remains a prevalent condition worldwide and is associated with a wide spectrum of adverse maternal and perinatal outcomes. Maternal anemia has been linked to increased risk of postpartum anemia, need for blood transfusion, impaired physical recovery after delivery, prolonged hospital stay, and reduced quality of life in the puerperium. From a healthcare system perspective, anemia management close to delivery has important implications for resource utilization and patient safety.

Recent National Guidelines have updated the diagnostic thresholds for anemia in pregnancy, defining anemia as hemoglobin (Hb) <11 g/dL throughout gestation, including the third trimester. As a result, a growing number of women are diagnosed with anemia late in pregnancy, often after 34 weeks of gestation, when the time window for hematologic correction before delivery is limited.

In this setting, intravenous (IV) iron therapy is increasingly used to achieve a rapid increase in hemoglobin levels. While IV iron is effective and generally safe, it is associated with higher costs, need for monitored administration, and a small but non-negligible risk of hypersensitivity reactions. Importantly, the routine early use of IV iron in women diagnosed late in pregnancy is not uniformly supported by high-quality randomized evidence.

Oral iron remains the recommended first-line therapy for iron-deficiency anemia in pregnancy. However, the effectiveness of oral iron when initiated in late gestation is often questioned, leading to premature escalation to IV therapy without a documented trial of oral treatment. There is limited prospective evidence assessing whether oral iron, when promptly initiated after late diagnosis, can still achieve clinically meaningful hemoglobin improvements before delivery.

A step-up treatment strategy, consisting of oral iron as initial therapy with escalation to IV iron only in case of inadequate response, may represent a balanced approach that aligns with guideline recommendations, minimizes overtreatment, and preserves patient safety. However, this strategy has not been adequately evaluated in randomized controlled trials focusing specifically on late-diagnosed anemia.