Relationship Between Maternal Iron Indices in the Second Trimester with Cord Blood Iron Indices and Pregnancy Outcomes: A Prospective Cohort Study

<b>Background/Objectives:</b> Iron deficiency anemia in pregnancy poses risks to mothers and infants. This study aimed to correlate maternal iron indices in the second trimester with cord blood indices and pregnancy outcomes. <b>Methods:</b> This prospective cohort study was nested within the RAPIDIRON Trial (Reducing Anaemia in Pregnancy in India) at Jawaharlal Nehru Medical College, Karnataka, India. A total of 292 pregnant women with moderate anemia who received oral iron supplementation were enrolled from April 2021 to May 2023. Maternal iron indices were measured at multiple time points and correlated with cord blood indices and pregnancy outcomes. <b>Results:</b> Increased hemoglobin levels were observed in mothers of preterm and term neonates from 8.92 ± 0.81 vs. 9.02 ± 0.77 g/dL at 12-16 weeks to 11.14 ± 1.31 vs. 10.73 ± 1.24 g/dL at 26-30 weeks. A similar trend was observed in mothers across birth weight groups. Ferritin and TSAT levels significantly increased in all outcome groups (<i>p</i> < 0.001), peaking at 20-24 weeks and then slightly declining at 26-30 weeks. Additionally, maternal sTfR levels significantly improved from the early (7.72 ± 1.33 vs. 7.51 ± 1.61) to late second trimester (5.87 ± 0.81 vs. 5.76 ± 1.11) in mothers of both anemic and non-anemic neonates (<i>p</i> < 0.001). Maternal sTfR in other outcome groups also showed a similar pattern. A negligible correlation was found between maternal and cord blood iron indices. <b>Conclusions:</b> Maternal iron indices increased from the early to mid-second trimester, followed by a slight fall in the late second trimester. Notably, higher iron indices were observed in mothers of preterm and low-birth-weight neonates.