Effects of latent iron deficiency on auditory neural maturation during early infancy in infants above 35 weeks? gestation

Background: Latent iron deficiency (LID) at birth is associated with prolonged latencies in audi-tory brainstem response (ABR), a surrogate for neural maturation. This study aimed to compare wave and inter-peak latencies of ABR at birth and at 4-6 months of age in infants >35 weeks of gestation with normal iron status (NIS) and LID. Methods: Neonates born at >35 weeks were screened. Cord ferritin value < 75 ng/mL and >75 ng/mL were classified as LID and NIS, respectively. ABR was performed within 48 h of birth. The absolute latencies of waves I, III, and V, and inter-peak latencies I-III, III-V, and I-V were computed. Infants were reassessed at 4-6 months of age for hemoglobin, serum ferritin levels, and ABR latencies. Results: In total, 160 neonates were enrolled. The mean (SD) birth weight and gestational age of the study population were 2843 (384) g and 38.3 (1.1) weeks, respectively. Approximately 122 infants completed follow-up until 4-6 months of age: 37 in the LID group and 85 in the NIS group. Overall, the wave and interpeak latencies in both groups at birth were comparable. At 4-6 months, the absolute latencies of waves I, III, and V, and inter-peak latencies I-III, III-V, and I-V were decreased and were comparable in both groups. Among small-for-gestational-age neonates, inter-peak latencies in I-III and I-V at birth were significantly longer in the LID group than in the NIS group. Nine (24.3%) infants in the LID group and none in the NIS group were iron -deficient at 4-6 months of age. Conclusion: There was no difference in wave or inter-peak latencies at birth and at 4-6 months of age in neonates aged >35 weeks with or without LID. However, infants with LID at birth have a significant risk of iron deficiency at 4-6 months of age. CTRI/2017/08/009379 (www.ctri.nic.in).Copyright (c) 2022, Taiwan Pediatric Association. Published by Elsevier Taiwan LLC. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/ by-nc-nd/4.0/).