Mild maturational delay of the brainstem at term in late preterm small-for-gestation age babies

•The effect of intrauterine growth retardation on the immature brainstem auditory pathway in late preterm babies is unclear.•We found marginal abnormalities in maximum length sequence brainstem evoked response in late preterm babies born of SGA.•The abnormalities suggest a mild degree of maturational delay in the brainstem auditory pathway in these babies.•Intrauterine growth retardation has a minor effect on auditory neural maturation of the brainstem in late preterm babies.

AimsTo detect any functional abnormality in the brainstem auditory pathway in late preterm babies born of small-for-gestational age (SGA) using maximum length sequence brainstem evoked response.Study designThe response was recorded and analyzed at term in 38 SGA (birthweight < 3rd centile) babies born at 33–36 week gestation. The results were compared with 40 age-matched babies born of appropriate-for-gestational age (AGA) (birthweight > 10th centile). None of the subjects had major perinatal problems.ResultsAll wave latencies and interpeak intervals in the SGA group were slightly longer than those in the AGA group at most click rates. Wave III latency was significantly longer than that in the AGA group at 227/s (P < 0.05), and wave V latency was at 227 and 910/s (P < 0.05 and 0.05). Of the interpeak intervals, only the I–V interval in the SGA group was significantly longer than that in the AGA group at the highest rate 910/s (P < 0.05). The amplitudes of waves I, III and V in the SGA group all tended to be smaller than those in the AGA group at all click rates 91–910/s. The wave V amplitude was significantly smaller at most click rates (227–910/s, all P < 0.05). The slopes of all wave latency–, interval–, and amplitude–rate functions were similar in SGA and AGA groups.ConclusionsThere were marginal abnormalities in MLS BAER of low-risk late preterm SGA babies, suggesting a mild degree of maturational delay in the brainstem. Intrauterine growth retardation occurring in late preterm babies has a minor effect on neural maturation of the immature brainstem.