Interfacility Variation in Diagnosis and Tocolysis for Threatened Preterm Labor and Its Association With Gestational Age Threshold for Neonatal Intensive Care Unit Admission: A Cross‐Sectional Survey of Perinatal Centers in the Chugoku–Shikoku Region

AIM: To describe interfacility variation in threatened preterm labor (TPL) management in a perinatal care network in western Japan and the association between the neonatal intensive care unit (NICU) admission threshold and the long-term tocolysis policy. METHODS: A cross-sectional, facility-level questionnaire survey was conducted for all 43 perinatal maternal and child health centers in the Chugoku-Shikoku region of western Japan in 2024. Centers reported diagnostic criteria for TPL, use of objective scoring systems, first-line intravenous tocolytic drugs, NICU admission gestational age threshold, and institutional policies regarding planned duration of intravenous tocolysis (short-term, ≤ 48 h; long-term, > 48 h). Factors related to the adoption of long-term tocolysis were evaluated using logistic regression. RESULTS: Valid responses were obtained from 32 centers (74.4%). A long-term-only tocolysis policy was reported by 65.6% (21/32) of centers. Diagnostic criteria and thresholds for intervention varied widely, and only three centers (9.4%) used an objective severity score, such as the preterm labor index or tocolysis index. Ritodrine hydrochloride was used as the first-line intravenous tocolytic drug in 93.8% (30/32) of centers. The NICU admission threshold differed among centers. In multivariable analysis, centers with a higher NICU admission threshold were more likely to report a long-term-only policy (adjusted odds ratio, 1.38 per 1-week increase; 95% confidence interval, 1.04-1.83; p = 0.028). CONCLUSIONS: Management of TPL showed marked interfacility variation in the regional perinatal care network. The NICU admission threshold was associated with the institutional tocolysis-duration policy, suggesting that regional perinatal system structure should be considered when discussing optimal tocolysis duration.