MRI BRAIN lesions and growth after antenatal steroids in preterm infants: Does timing matter?

INTRODUCTION: Antenatal corticosteroids (ACS) are widely used to improve outcomes in preterm infants, with known benefits on respiratory morbidity and intraventricular hemorrhage (IVH). However, the effect of ACS timing on brain injury and development remains unclear. We aimed to evaluate the impact of a complete course of ACS (ccACS), with particular attention to timing, on brain lesions, growth, and neurodevelopment in very low birth weight (VLBW) infants using magnetic resonance imaging (MRI). MATERIAL AND METHODS: In this historical cohort study, all VLBW infants admitted to a tertiary neonatal intensive care unit between January 2019 and December 2021 were included. Clinical data, including timing of ACS administration, were collected. The primary outcome was the occurrence of brain injury on MRI at term-equivalent age, including IVH, white matter lesions (WML), and cerebellar hemorrhage (CBH). Secondary outcomes were brain growth and maturation on MRI and neurodevelopment at 2 years assessed using the Griffiths Mental Development Scales. Outcomes were compared between infants with and without ccACS and according to different administration-to-birth intervals. RESULTS: A total of 189 infants were included, of whom 139 (73.5%) received ccACS. Infants exposed to ccACS had a lower incidence of WML (p = 0.02) and moderate/severe IVH (p = 0.04). In extremely preterm infants (<28 weeks), IVH was significantly less frequent when ccACS was administered within 7 days before birth (p = 0.006). No significant differences were observed in brain growth, maturation, or neurodevelopmental outcomes at 2 years. CONCLUSIONS: A complete course of ACS was associated with unadjusted lower rates of brain injury in VLBW infants, particularly when administered within 7 days before birth in extremely preterm infants, without adverse effects on brain growth, maturation, or neurodevelopment at 2 years.