Association of antenatal corticosteroid therapy on women with clinical chorioamnionitis: A nationwide cohort study in Japan.

INTRODUCTION: Antenatal corticosteroids (ACS) prevent neonatal complications and mortality in women at risk of preterm birth. However, the benefits and risks of ACS in chorioamnionitis (CAM) remain debated. This study evaluated whether ACS in women with clinical CAM was associated with adverse neonatal outcomes. METHODS: This population-based retrospective study included neonates born before 34 weeks of gestation to women with clinical CAM in Japan between April 2010 and March 2023. Data were obtained from the Neonatal Research Network of Japan database. Adjusted odds ratios (aOR) for mortality and morbidity were compared between ACS and non-ACS groups. RESULTS: Of the 6,158 preterm infants born to mothers with clinical CAM, 4,086 (66.4%) received ACS and 2,072 (33.6%) did not. ACS exposure was associated with reduced aORs for respiratory distress syndrome (RDS; aOR: 0.85; 95% confidence interval [CI]: 0.75-0.96), intraventricular hemorrhage (IVH) grade III/IV (aOR: 0.52; 95% CI: 0.41-0.66), periventricular leukomalacia (PVL; aOR: 0.71; 95% CI: 0.54-0.95), sepsis (aOR: 0.78; 95% CI: 0.66-0.92), treated retinopathy of prematurity (ROP; aOR: 0.81; 95% CI: 0.69-0.95), and mortality (aOR: 0.69; 95% CI: 0.55-0.87). In contrast, the aOR for bronchopulmonary dysplasia (BPD) was higher in the ACS group (aOR: 1.51; 95% CI: 1.31-1.73). CONCLUSION: ACS treatment in women with clinical CAM was associated with reduced neonatal death, RDS, severe IVH, PVL, sepsis, and ROP while increasing the risk of BPD. These findings support ACS therapy while underscoring the need for further studies to identify interventions beyond ACS to prevent BPD.