Ultrasound measurements of brain structures differ between moderate-late preterm and full-term infants at term equivalent age

Background: Brain growth in moderate preterm (MP; gestational age (GA) 32⁺⁰-33⁺⁶ weeks) and late preterm infants (LP; GA 34⁺⁰-36⁺⁶ weeks) may be impaired, even in the absence of brain injury.

Aims: The aims of this study were to assess brain measurements of MP and LP infants, and to compare these with full-term infants (GA > 37 weeks) using linear cranial ultrasound (cUS) at term equivalent age (TEA).

Study design: cUS data from two prospective cohorts were combined. Two investigators performed offline measurements on standard cUS planes. Eleven brain structures were compared between MP, LP and full-term infants using uni- and multivariable linear regression. Results were adjusted for postmenstrual age at cUS and corrected for multiple testing.

Results: Brain measurements of 44 MP, 54 LP and 52 full-term infants were determined on cUS scans at TEA. Biparietal diameter and basal ganglia-insula width were smaller in MP (-9.1 mm and - 1.7 mm, p < 0.001) and LP infants (-7.0 mm and - 1.7 mm, p < 0.001) compared to full-term infants. Corpus callosum - fastigium length was larger in MP (+2.2 mm, p < 0.001) than in full-term infants. No significant differences were found between MP and LP infants.

Conclusions: These findings suggest that brain growth in MP and LP infants differs from full-term infants. Whether these differences have clinical implications remains to be investigated.