In Utero Iron Status and Auditory Neural Maturation in Premature Infants as Evaluated by Auditory Brainstem Response

Abstract

To determine whether cord ferritin (CF) concentration, an index of in utero iron status, is associated with auditory neural maturation in premature infants. A prospective cohort study was performed to compare auditory neural maturation in infants with latent iron deficiency (CF 11-75 ng/mL) and infants with normal iron status (CF > 75 ng/mL) at birth. Our inclusion criteria were infants of 27-33 weeks gestational age who were admitted to the neonatal intensive care unit between July 2007 and November 2008 within 12 hours after birth and had cord blood collected. Infants with TORCH infections (toxoplasmosis, other infections, rubella, cytomegalovirus infection, and herpes simplex), chromosomal disorders, craniofacial anomalies, culture-proven sepsis, and/or unstable conditions were excluded. CF level was measured using a chemiluminescence immunoassay method. Bilateral monaural auditory brainstem evoked response (ABR) was assessed using 80-dB nHL click stimuli at a repetition rate of 29.9/seconds within 48 hours after birth. Of the 80 infants studied, 35 had latent iron deficiency. After controlling for confounders, the infants with latent iron deficiency had significantly prolonged absolute wave latencies I, III, and V and decreased frequency of mature ABR waveforms compared with the infants with normal iron status. Premature infants with in utero latent iron deficiency have abnormal auditory neural maturation compared with infants with normal in utero iron status.