Latent Iron Deficiency In Utero Is Associated with Abnormal Auditory Neural Myelination in ≥35 Weeks Gestational Age Infants

Objective To determine whether cord serum ferritin level is associated with auditory brainstem evoked response interpeak latencies, an index of auditory neural myelination, in infants at ≥35 weeks gestational age (GA). Study design This prospective study compared auditory neural myelination in infants with latent iron deficiency (cord serum ferritin, 11-75 ng/mL) and infants with normal iron status (cord serum ferritin, >75 ng/mL) at birth. Our inclusion criteria were infants born at ≥35 weeks GA who had cord blood collected soon after birth and had 1 or more of the following risk factors for poor in utero iron status: maternal diabetes mellitus, pregnancy-induced hypertension, and intrauterine growth restriction. Cord serum ferritin level was measured using the chemiluminescence immunoassay method. Auditory brainstem evoked response was measured using 80-dB normal hearing level click stimuli at a rate of 69.9/second within 48 hours after birth to evaluate interpeak latencies, a measure of nerve conduction velocity or myelination. Results Of the 45 infants studied, 12 had latent iron deficiency. On repeated-measures ANCOVA using interpeak latencies I-III, III-V, and I-V as multiple outcomes, infants with latent iron deficiency had significantly prolonged interpeak latencies ( P = .01) compared with infants with normal iron status after controlling for confounders. Conclusion In utero latent iron deficiency is associated with abnormal auditory neural myelination at birth in infants born at ≥35 weeks GA.