Sex and gestational age effects on auditory brainstem responses in preterm and term infants

Background: Some studies find delayed development of the auditory brainstem in preterm infants, but others do not.

Aim: To compare auditory brainstem responses (ABRs) in healthy preterm and term infants depending on sex and gestational age (GA).

Methods: Participants were 111 preterm (27-36weeks GA) and 92 term (37-41weeks GA) infants. ABR tests were conducted at 6weeks (corrected age if preterm).

Results: There were no overall differences between term and preterm groups in ABRs. However, males showed longer latencies for waves III, V, and I-III, III-V, and I-V intervals and smaller amplitudes for wave III and V than females in both preterm and term groups (all p values≤.01). A 3-way interaction between group, sex, and GA (p<.05) showed that preterm males with later GA had longer wave I-V interval, whereas term females with later GA showed shorter wave I-V interval. Growth velocity predicted wave I-V interval in preterm infants, controlling for other factors (male: p=.07, female: p<.05).

Conclusion: ABRs in preterm and term infants were similar at 6weeks (corrected age if preterm), but males had less advanced ABRs than females. More rapid growth predicted less mature ABR in later GA preterm infants in this setting where they were unlikely to receive extra iron. The roles of GA, growth, and iron balance in ABR development warrant further study.