Preterm birth (PTB) is a major global cause of neonatal morbidity and mortality, and its incidence has remained largely unchanged. Antenatal corticosteroids (ACS) are the most effective intervention for improving outcomes in pregnancies at risk of PTB, enhancing fetal lung maturation and reducing respiratory and neurological complications. A single ACS course is recommended before 34 weeks, although interest has expanded to late preterm and periviable gestations. While short-term respiratory benefits in late preterm infants are well documented, uncertainties remain regarding optimal timing, dosing, and long-term developmental effects. Both endogenous and exogenous glucocorticoids play key in fetal maturation but can influence neurodevelopmental programming when exposure exceeds physiologic levels. ACS affects the fetal HPA axis, placental function, neural stem/progenitor cells, and epigenetic regulation, with potential implications for later cognitive, behavioral, and metabolic outcomes. Repeated ACS courses offer no clear neonatal benefit and may reduce birth weight or increase neurodevelopmental risks. Given the importance of administering ACS within 2–7 days before delivery, accurate prediction of imminent PTB is essential. Emerging predictive models and ongoing large cohort studies are expected to refine gestational age specific recommendations. ACS remains a cornerstone of PTB management, requiring individualized, evidence-based use.