# Differential linear brain growth patterns in preterm neonates based on birth gestational age and steroid exposure: A retrospective chart review

## TL;DR

This study finds that extremely preterm infants have smaller brain structures compared to very preterm infants at term age, and antenatal steroids may negatively affect brain growth.

## Contribution

The study identifies specific brain growth differences based on gestational age and antenatal steroid exposure in preterm infants.

## Key findings

- Extremely preterm infants have smaller biparietal diameter, corpus-callosum length, and cerebellar-vermis height compared to very preterm infants.
- Antenatal steroid exposure is negatively associated with corpus-callosum length and pons anteroposterior depth.
- Postnatal steroid exposure does not significantly affect brain metrics.

## Abstract

To assess the differences in brain growth between extreme preterm [EP](22–28wks gestation age [GA]) and very preterm infants [VP](28+1–32wks GA) using two-dimensional cranial ultrasound(cUS) at term equivalence.

Retrospective study of neonates born at GA of ≤ 32 weeks between 1st January 2019 and 31st December 2022, without major parenchymal brain injury.

326 neonates, with 207 EP and 119 VP, were enrolled. EP infants compared to VP had significantly lower biparietal diameter [7.7vs7.9 cm, p = 0.003], corpus-callosum length [3.8vs4.1 cm, p < 0.001], corpus-callosum-fastigial distance [4.5vs4.8 cm, p = 0.004] and cerebellar-vermis height [2.1vs2.2 cm, p = 0.002]. Cumulative postnatal steroid exposure had no significant association with brain metrics; however, exposure to antenatal steroids was negatively associated with corpus-callosum length [β = −0.38 (−0.58 to −0.7),p = 0.0003] and pons anteroposterior depth [β = −0.36 (−0.47 to −0.25),p < 0.0001] despite adjustments for clinically important risk factors.

Preterm infants born ≤ 28 weeks GA have significantly smaller dimensions of major white matter tracts than preterm infants born 28–32 weeks GA at term equivalence. Exposure to antenatal steroids negatively impacts corpus-callosum length and pons anteroposterior depth.