IV iron supplementation, dosage, and timing in pregnancy: A single-institution review on a maternal transfusion...

Little is known about the effects of intravenous iron (IVFe) supplementation on maternal hemoglobin (Hb) by timing of infusion and dosage.

To identify the association of IVFe timing and dose on pre-delivery Hb.

A retrospective cohort study of pregnant patients with iron deficiency anemia (IDA) who received iron sucrose (Venofer®) at our Level IV maternity care center following the implementation of a quality improvement (QI) transfusion reduction bundle from January 2020 to December 2023. The primary outcome was the association between IVFe timing and pre-delivery Hb. Secondary outcomes included the impact of IVFe dosage and infusion-to-delivery interval on Hb. Statistical analyses included paired t-tests, Mann-Whitney U tests, χ² tests, ANOVA, and post-hoc Tukey multiple comparisons (significance set at p < 0.05).

295 patients were included. Mean age, BMI, and ferritin were 26.6 ± 6.3 years, 28.1, and 7.2 ± 7.8 μg/L, respectively. Mean GA for IVFe administration was 34 weeks. Two patients required intrapartum/postpartum red blood cell transfusions. A greater mean Hb difference (2.5 g/dL vs 1.3 g/dL), was observed with IVFe at <34 weeks compared to ≥34 weeks (p < 0.001). Higher IVFe doses were associated with increased pre-delivery Hb levels (p = 0.002) and a longer infusion-to-delivery interval (p = 0.049). The strongest Hb improvement was seen with latency from ≥6-8 weeks with doses >800 mg versus <2 weeks at doses ≤ 800 mg (increase of 2.6 - 3.1 g/dL, p < 0.0001).

Substantial benefit is seen when IVFe is given in the early third trimester, especially with ≥6 weeks of latency and doses ≥800 mg.