{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,30]],"date-time":"2026-07-30T06:01:43Z","timestamp":1785391303978,"version":"3.55.0"},"reference-count":22,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,7,30]],"date-time":"2026-07-30T00:00:00Z","timestamp":1785369600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Reprod. Health"],"abstract":"<jats:p>Preterm birth remains a major perinatal challenge, and management of women presenting with symptoms suggestive of early labor can shape admission, monitoring, medication use, and transfer pathways. In contemporary international practice, threatened preterm labor is generally managed within a risk-stratified framework, and tocolysis is used mainly for short-term obstetric purposes such as antenatal corticosteroid completion, maternal transfer, and fetal neuroprotection. In Japan, however, threatened preterm labor has often been diagnosed across a relatively broad clinical spectrum and managed with prolonged inpatient observation, bed rest, and extended ritodrine-based tocolysis. This review examines that pattern as a policy and practice problem rather than a narrow therapeutic controversy. It argues that the Japanese approach reflects a persistent evidence\u2013practice gap involving broad diagnostic labeling, limited evidence supporting routine maintenance ritodrine, heterogeneous real-world practice, and guideline wording that remains more permissive than prohibitive. The available literature does not support prolonged maintenance ritodrine as routine care, while associations with maternal and neonatal safety concerns have been increasingly reported. Persistence is interpreted as potentially related to diagnostic breadth, institutional routines, limited therapeutic pathways, and uncertainty about de-escalation, not as evidence of a single cultural or medico-legal cause. This review proposes clearer negative recommendations on prolonged maintenance ritodrine, stronger diagnostic precision, and operational protocols that distinguish high-risk women requiring inpatient care from lower-risk women suitable for reassessment, treatment reduction, or outpatient follow-up.<\/jats:p>","DOI":"10.3389\/frph.2026.1883392","type":"journal-article","created":{"date-parts":[[2026,7,30]],"date-time":"2026-07-30T05:39:11Z","timestamp":1785389951000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["Threatened preterm labor in Japan: an evidence\u2013practice gap in diagnosis, tocolysis, and guideline implementation"],"prefix":"10.3389","volume":"8","author":[{"given":"Katsuaki","family":"Inami","sequence":"first","affiliation":[{"name":"Department of Obstetrics and Gynecology, Fujinomiya City General Hospital","place":["Fujinomiya, Japan"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2026,7,30]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","first-page":"1261","DOI":"10.1016\/S0140-6736(23)00878-4","article-title":"National, regional, and global estimates of preterm birth in 2020, with trends from 2010: a systematic analysis","volume":"402","author":"Ohuma","year":"2023","journal-title":"Lancet"},{"key":"B2","doi-asserted-by":"publisher","first-page":"12839","DOI":"10.1038\/s41598-023-38524-9","article-title":"Association between gestational age at threatened preterm birth diagnosis and incidence of preterm birth: the Japan environment and children\u2019s study","volume":"13","author":"Murata","year":"2023","journal-title":"Sci Rep"},{"key":"B3","doi-asserted-by":"publisher","first-page":"204","DOI":"10.1186\/s12884-019-2352-1","article-title":"Inappropriate use of ritodrine hydrochloride for threatened preterm birth in Japan: a retrospective cohort study using a national inpatient database","volume":"19","author":"Shigemi","year":"2019","journal-title":"BMC Pregnancy Childbirth"},{"key":"B4","doi-asserted-by":"publisher","first-page":"22633","DOI":"10.1038\/s41598-025-07530-4","article-title":"Prolonged administration of ritodrine hydrochloride in women with premature labor or threatened premature delivery based on empirical data in Japan","volume":"15","author":"Ogawa","year":"2025","journal-title":"Sci Rep"},{"key":"B5","doi-asserted-by":"publisher","first-page":"3758","DOI":"10.1111\/jog.14951","article-title":"Report from \u201cinternational workshop for junior fellows 2: tocolytic treatment for prevention of preterm birth\u201d at the 73rd annual congress of the Japan society of obstetrics and gynecology","volume":"47","author":"Murata","year":"2021","journal-title":"J Obstet Gynaecol Res"},{"key":"B6","volume-title":"WHO recommendation on Tocolytic Therapy for Improving Preterm Birth Outcomes","year":"2022"},{"key":"B7","volume-title":"Preterm Labour and Birth. 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