title: Changes in hearing threshold between 28 and 42 weeks of age in babies born at under 30 weeks of gestation.
abstract: OBJECTIVE
  This study aimed to describe changes in hearing thresholds in babies born below 30 weeks of gestation at 28-42 weeks of postconceptional age, detect differences between gestational ages and explore the prevalence of hearing impairment.
  
  
  METHODS
  The threshold of brainstem auditory evoked response (BAER) was obtained longitudinally at 28-42 weeks of postconceptional age in 71 babies born at 23-29 weeks of gestation.
  
  
  RESULTS
  The BAER threshold was 28 decibels above normal hearing level (dB nHL) at 28 weeks of postconceptional age and decreased to 13 dB nHL at 39-42 weeks. The threshold was slightly higher in babies born at 23-26 weeks of gestation than in those born at 27-29 weeks at most postconceptional ages studied. From 28 to 36 weeks, the threshold decreased at 0.98 dB/week. At term, BAER threshold elevation (>20 dB nHL) occurred in 12 (16.9%) of the 71 babies.
  
  
  CONCLUSIONS
  The hearing threshold of babies born at 23-29 weeks of gestation decreased from 28 dB at 28 weeks of postconceptional age to 13 dB at 42 weeks. There were no major differences between gestational ages. During the preterm period, the threshold changed at around 1 dB/week. At term, one in six babies had hearing impairment.
authors.affiliation: Division of Neonatology, Children's Hospital, Fudan University, Shanghai, China; Neonatal Unit, Department of Paediatrics, John Radcliffe Hospital, Oxford, UK.
authors.forename: Ze D
authors.initials: ZD
authors.lastname: Jiang
authors.forename: Rong
authors.initials: R
authors.lastname: Yin
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Wilkinson
mesh_terms: D001309:Auditory Threshold; D016057:Evoked Potentials, Auditory, Brain Stem; D005260:Female; D005865:Gestational Age; D034381:Hearing Loss / Q000175:diagnosis* / Q000453:epidemiology*; D006801:Humans; D007223:Infant; D007235:Infant, Premature, Diseases / Q000175:diagnosis* / Q000453:epidemiology*; D008297:Male; D015995:Prevalence; D011446:Prospective Studies
keywords: Brainstem auditory evoked response; Hearing impairment; Neonatal hearing screening; Very preterm