Trends in ritodrine prescriptions among pregnant women in Japan: a nationwide descriptive analysis of an administrative hospital database from 2015 to 2024.

Authors

Daisuke Kikuchi, Taku Obara, Aoi Noda, Takamasa Sakai, Chiemi Ogura, Keiko Minato, Ami Murata, Naoko Matsuda, Kouji Okada, Atsuko Tominaga, Yuriko Murai

Published in

The journal of maternal-fetal & neonatal medicine : the official journal of the European Association of Perinatal Medicine, the Federation of Asia and Oceania Perinatal Societies, the International Society of Perinatal Obstetricians. Volume 39. Issue 1. Pages 2701547. Epub Jul 13, 2026.

Abstract

Ritodrine hydrochloride has been widely used in Japan to treat threatened preterm labor, often beyond the internationally recommended short-term duration. Accumulating evidence has demonstrated limited benefits and raised safety concerns regarding prolonged ritodrine administration, and a declining trend in its use has been documented through 2021. However, prescribing trends following the March 2021 revision of the ritodrine package insert remain unclear. Here, we investigated recent nationwide trends in ritodrine prescriptions among pregnant women in Japan from 2015 to 2024, with particular focus on trends after 2021, and examined differences according to route of administration and healthcare setting.
Administrative data on pregnant Japanese women who visited acute-care Diagnosis Procedure Combination (DPC) hospitals between January 1, 2015, and December 31, 2024, were used in this study. The analysis focused on ritodrine products marketed in Japan. The prevalence of ritodrine prescriptions was analyzed, and temporal trends were assessed using the Cochran-Armitage trend test. Stratified analyses were performed according to age group, hospital bed capacity, and hospital type.
Among hospitalized pregnant women, the prevalence of oral ritodrine prescriptions decreased from 22.0% to 17.2% (absolute decrease of 4.8 percentage points, p < 0.001) during the study period (2015-2024), whereas that of injectable ritodrine prescriptions decreased from 37.6% to 25.0% (absolute decrease of 12.6 percentage points, p < 0.001). Among pregnant outpatients, the prevalence of oral ritodrine prescriptions decreased from 58.5% to 34.5% (absolute decrease of 24.0 percentage points, p < 0.001), whereas that of injectable ritodrine prescriptions increased slightly from 0.42% to 0.46% (absolute increase of 0.04 percentage points, p = 0.01), although outpatient injectable ritodrine prescribing remained below 1% throughout the study period. The decline was more pronounced for oral ritodrine prescriptions than for injectable ritodrine prescriptions.
Ritodrine prescriptions among pregnant women in Japan decreased between 2015 and 2024 for both oral and injectable formulations in hospitalized settings and for oral formulations in outpatient settings. The decline continued after the 2021 package insert revision, suggesting ongoing changes in prescribing practices related to prolonged ritodrine use.

PMID:
42443054
Bibliographic data and abstract were imported from PubMed on 14 Jul 2026.

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