Prenatal Intravenous Iron and Child Growth: A Secondary Analysis of a Randomized Clinical Trial.

Importance: Maternal anemia during pregnancy is associated with poor growth during early childhood, but it remains unclear whether treatment using intravenous iron could enhance child growth. Objective: To evaluate whether intravenous ferric carboxymaltose (FCM) treatment for moderate to severe anemia during the second trimester of pregnancy enhances postnatal child growth compared with standard-of-care (SOC) oral iron. Design, Setting, and Participants: This was a prespecified secondary analysis of a randomized clinical trial (Randomized Controlled Trial of the Effect of Intravenous Iron on Anaemia in Malawian Pregnant Women [REVAMP]). In REVAMP, pregnant women with capillary hemoglobin between 5 and 10 g/dL were recruited in the Blantyre and Zomba districts of southern Malawi between November 2018 and March 2022 and randomized to FCM or SOC. Their infants were followed up over 12 months post partum. Data analysis was conducted between August 2024 and August 2025. Intervention: Mothers were given intravenous FCM up to 1000 mg once on trial enrollment (intervention group) or SOC oral ferrous sulfate, 200 mg twice daily (approximately 120 mg elemental iron per day) (control group) from 13 to 26 weeks' gestation until delivery. Children received no intervention. Main Outcomes and Measures: Length-for-age z score (LAZ) at 12 months was the primary growth outcome; secondary outcomes included weight-for-age z scores (WAZ), weight-for-length z scores (WLZ), stunting (LAZ <-2), underweight (WAZ <-2), and wasting (WLZ <-2). Length and weight were measured at birth and at 1, 3, 6, 9, and 12 months post partum. The repeated measures were analyzed using mixed-effects models. Results: A total of 738 infants were followed up for 12 months between March 2019 and October 2022. A total of 371 (193 [52.0%] male; mean [SD] gestational age at birth, 39.5 [1.9] weeks) were in the FCM group, and 367 (187 [51.2%] male; mean [SD] gestational age at birth, 39.4 [2.3] weeks) were in the SOC group. There was no evidence of a difference between FCM and SOC groups in mean LAZ (mean difference, -0.15 [95% CI, -0.37 to 0.08]), WAZ (mean difference, -0.02 [95% CI, -0.21 to 0.16]) or WLZ (mean difference, 0.02 [95% CI, -0.20 to 0.24]) at 12 months. Similarly, there was no difference in the proportion with stunting, underweight, or wasting at all time points. Stunting was more common in mothers younger than 20 years, less than 150 cm in height, and with no education or primary education only, although treatment effects showed no evidence of heterogeneity. Conclusions and Relevance: In this secondary analysis of a randomized clinical trial in southern Malawi, intravenous FCM treatment for moderate to severe anemia during the second trimester of pregnancy was not associated with substantial benefits on infant growth compared with SOC. Trial Registration: anzctr.org.au Identifier: ACTRN12618001268235.