Comparison of maturational process of hearing threshold in early life between at-risk and low-risk preterm infants

Abstract Aim To detect any abnormality in the maturational process of hearing threshold during the early life in at-risk preterm infants. Study design The threshold of brainstem auditory evoked response was recorded and analyzed longitudinally from 30 to 42 weeks of postconceptional age in 357 at-risk infants born at 23–36 weeks of gestation. The results were compared with those in 82 low-risk infants born at 30–42 weeks at various postconceptional ages. Results From 31 to 42 weeks, the response threshold in the at-risk infants was consistently slightly higher than that in the low-risk infants. No statistically significant difference was found between the two groups of infants at any designated postconceptional ages. The threshold in the at-risk infants born at 23–29 weeks of gestation tended to be higher than those born at 30–36 weeks at various postconceptional ages, but the difference did not reach statistical significance. There was also no significant difference in the slope of BAER threshold-age function between the at-risk infants, irrespective of gestational ages, and the low-risk infants. Conclusion During the early life, hearing threshold in at-risk preterm, mainly very preterm, infants is marginally elevated, but the maturational process of the threshold is generally similar to that in low-risk infants, without notable abnormality.