Changes in hearing threshold between 28 and 42 weeks of age in babies born at under 30 weeks of gestation
Ze D Jiang1, Rong Yin, Andrew R Wilkinson
1Division of Neonatology, Children's Hospital, Fudan University, Shanghai, China; Neonatal Unit, Department of Paediatrics, John Radcliffe Hospital, Oxford, UK.
Insights
Hearing thresholds in preterm infants improve significantly from 28 to 42 weeks postconceptional age. One in six extremely preterm babies experience hearing impairment by term age.
Area of Science:
- Neonatal audiology
- Developmental pediatrics
- Neuroscience
Background:
- Premature infants, especially those born before 30 weeks gestation, are at higher risk for hearing deficits.
- Early detection and monitoring of hearing development in this vulnerable population are crucial for timely intervention.
Purpose of the Study:
- To track hearing threshold changes in preterm infants (born <30 weeks gestation) from 28 to 42 weeks postconceptional age.
- To identify differences in hearing development based on gestational age at birth.
- To determine the prevalence of hearing impairment in this cohort at term equivalent age.
Main Methods:
- Longitudinal brainstem auditory evoked response (BAER) testing was performed on 71 infants born between 23-29 weeks gestation.
- Hearing thresholds were assessed between 28 and 42 weeks of postconceptional age.
Main Results:
- BAER thresholds improved from 28 dB nHL at 28 weeks to 13 dB nHL at 39-42 weeks postconceptional age.
- A slight increase in threshold was observed in infants born at 23-26 weeks compared to 27-29 weeks gestation.
- Hearing threshold improved by approximately 1 dB/week between 28-36 weeks postconceptional age.
- By term equivalent age, 16.9% (12/71) of infants exhibited elevated BAER thresholds (>20 dB nHL), indicating hearing impairment.
Conclusions:
- Hearing thresholds in preterm infants born at 23-29 weeks gestation show significant improvement, decreasing from 28 dB to 13 dB between 28 and 42 weeks postconceptional age.
- Minimal differences in hearing development were noted across the studied gestational ages.
- Approximately 1 dB/week improvement in hearing threshold occurs during the preterm period.
- The prevalence of hearing impairment at term equivalent age is approximately 1 in 6 infants.
Aim:
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.
Conclusion:
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.
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