There is broad consensus that maternal antenatal corticosteroid treatment (ACT) improves outcomes for babies born very (<32 weeks) or moderately (33–34 weeks) preterm. Although the short-term benefits of ACT are well established, its broad and systemic effects on fetal growth and development have raised concerns about potential long-term harms. While randomized clinical trials on the long-term effects of ACT have been reassuring, recent nationwide register-based cohort studies show that fetuses exposed to ACT have an increased risk of mental and behavioral disorders, neurosensory disorders, and infectious diseases later in life. However, several clinical knowledge gaps hinder the optimization and personalization of ACT to prevent or minimize long-term harms. This project will address these gaps, strengthen clinical research, support uptake of findings and improve healthcare delivery by optimizing and personalizing ACT use in real-world clinical practice.

2026

2029