Changes in brainstem auditory response threshold in preterm babies from birth to late term

Abstract

Conclusion: The hearing threshold in preterm infants was 23 dB above adult hearing level at 30 weeks gestation, and decreased to around 13 dB at term date. There was no major difference in the threshold for infants born at different gestations. At term, 9% had hearing threshold elevation. Objective: To examine changes in hearing threshold from preterm to term in infants born at 30–36 weeks gestation and to detect the prevalence of threshold elevation. Methods: The threshold in brainstem auditory evoked response (BAER) was obtained 656 times from postconceptional age (PCA) 30 to 42 weeks in 268 infants born at 30–36 weeks gestation. Results: The BAER threshold was 23 dB nHL at the youngest age (PCA 30 weeks), and then decreased to around 13 dB nHL at later preterm and term dates (PCA 35–42 weeks). The threshold was decreased with increasing age at a rate of 1.24 dB per week from PCA 30 to 36 weeks and 0.65 dB per week from PCA 30 to 42 weeks. At PCA 33–42 weeks, there were no significant differences in BAER threshold between the infants born at gestational age (GA) 30–32 weeks and those at GA 33–36 weeks. At term, 9% had threshold elevation (>20 dB nHL).

Keywords::

• Hearing threshold
• hearing development
• hearing impairment
• neonatal hearing screening
• preterm infant

Acknowledgments

We thank nurses and doctors at the Division of Neonatology, Children's Hospital, Fudan University and Neonatal Unit, John Radcliffe Hopistal, University of Oxford for their assistance in recruiting the subjects. This research was supported by grants from the Children's Hospital, Fudan University, and a State Scholarship of China, and Defeating Deafness, UK.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.