Facility‐Level Factors Associating Antenatal Corticosteroid Administration Rates and Subsequent Term Birth Rates: A Nationwide Cross‐Sectional Observational Study Using the 2020–2022 Perinatal Registry Database in Japan

Aim The antenatal corticosteroid (ACS) administration rate in Japan is low. To achieve both high coverage and low overtreatment of ACS, understanding of facility‐level factors is important. This study aimed to identify facility‐level factors associated with ACS coverage and overtreatment and simulate the potential consequences of increased ACS use. Methods This observational study used data from the 2020 to 2022 Perinatal Registry Database maintained by the Japan Society of Obstetrics and Gynecology. Primary outcomes were: (1) ACS administration rate among preterm births before 34 weeks (ACS/34w rate) and (2) proportion of term births among ACS recipients (term/ACS proportion). Multivariable regression analyses examined associations with facility‐level factors including perinatal care level, location, delivery volume, and prevalence of maternal conditions. A simulation estimated the impact of increasing ACS/34w rate to 80% in facilities with lower baseline rates. Results In the facility‐level analysis of 244 facilities (376 717 records), the mean ACS/34w rate was 63.4%, and term/ACS proportion was 12.0%. The proportion of threatened preterm labor (coefficient: 4.4 [95% confidence interval: 2.1–6.7]), deliveries < 34 weeks (3.0 [0.1–5.8]), and cesarean section rate (−2.4 [−4.5 to −0.2]) were significantly associated with ACS/34w rate. ACS/34w rate (2.0 [0.8–3.3]), annual delivery volume (2.1 [0.6–3.5]), and cesarean section rate (1.5 [0.2–2.7]) were positively associated with term/ACS proportion, while perinatal care level was inversely associated (−3.5 [−6.3 to −0.6]). Simulation estimated 2311 additional ACS recipients and 465 term births per year. Conclusions Facility‐level factors influence ACS coverage and overtreatment. These findings may inform strategies for optimizing ACS use.