Antenatal corticosteroid (ANC) use before 25 weeks’ gestation is controversial. Our previous systematic review (eight observational studies, n=10 109) showed that ANC exposure was associated with significantly reduced mortality and severe intraventricular haemorrhage (IVH)/periventricular leukomalacia (PVL) in neonates born <25 weeks. We update our review by adding data (n=3334) from a recent study. We used Cochrane methodology and summarised the results using GRADE (The Grading of Recommendations Assessment, Development and Evaluation) guidelines. Nine high-quality observational studies were included. Meta-analysis (random effects model) showed reduced mortality (n=13 443; OR=0.48 (95% CI 0.42 to 0.55) P<0.00001; level of evidence (LOE): moderate) and IVH or PVL (n=8418; OR=0.70 (95% CI 0.63 to 0.79), P<0.00001; LOE: moderate) in neonates born <25 weeks exposed to ANC. There was no difference in necrotising enterocolitis (NEC) ≥stage II (n=8737; OR=1.01 (95% CI 0.84 to 1.22), P=0.89; LOE: low); incidence of chronic lung disease (CLD) was higher (n=7983; OR=1.32 (95% CI 1.04 to 1.67), P=0.02; LOE: low) in ANC group. Composite outcomes of death/major morbidities (eg, severe IVH, NEC, CLD) were improved after ANC exposure.