Sedentary time during pregnancy and fetal malpresentation in the Japan Environment and Children’s Study
BACKGROUND: Fetal malpresentation, such as breech, transverse, and oblique presentations, is a frequent diagnosis in obstetrical practice. While several maternal factors have been studied, the potential relationship between maternal sedentary behavior and fetal malpresentation remains underexplored. This study aimed to examine the association between sedentary behavior during pregnancy and fetal malpresentation using data from a large longitudinal cohort study conducted in Japan. METHODS: This prospective longitudinal cohort study recruited approximately 100,000 pregnant women from 15 Regional Centers in Japan. Participants completed self-administered questionnaires in the first and either the second or third trimester of pregnancy. Sedentary behavior was defined as the number of hours spent sitting or lying down per day. The fetal presentation at delivery was recorded from medical records. Logistic regression analyses were conducted to estimate the odds ratio of the association between sedentary time and the likelihood of fetal malpresentation. RESULTS: Here we show that among 73,813 eligible participants, the mean maternal age is 31.3 years, 27.4% deliver at ≥35, 3.0% experience fetal malpresentation, and 48.7% have female infant. The median sedentary time is 5 hours (interquartile range: 3-8). Women who report ≥12 hours sedentary time per day have higher odds for fetal malpresentation compared to those reporting <6 hours (adjusted odds ratio: 1.17; 95% confidence interval: 1.02-1.35). CONCLUSIONS: The findings emphasize the need to address sedentary behavior as a modifiable risk factor during pregnancy, which may implicate future interventions aimed at reducing the incidence of fetal malpresentation.
Authors
- Toshihiro Kawamoto (ORCID: https://orcid.org/0000-0002-1168-4271)
- Kiyoko Kato (ORCID: https://orcid.org/0000-0003-0047-7637)
- Norio Hamada (ORCID: https://orcid.org/0000-0002-0906-8277)
- Ryo Kawasaki (ORCID: https://orcid.org/0000-0002-7492-6303)
- Reiko Suga (ORCID: https://orcid.org/0000-0002-8220-4941)
- Shouichi Ohga (ORCID: https://orcid.org/0000-0002-2426-7792)
- Takeo Nakayama (ORCID: https://orcid.org/0000-0002-7918-6252)
- Kimiyo Kikuchi (ORCID: https://orcid.org/0000-0002-9397-4327)
- Chisato Mori (ORCID: https://orcid.org/0000-0002-1144-8316)
- Masayuki Ochiai (ORCID: https://orcid.org/0000-0001-7169-3690)
- Narufumi Suganuma (ORCID: https://orcid.org/0000-0003-1610-6216)
- Seiji Kageyama (ORCID: https://orcid.org/0000-0002-5220-6137)
- Seiichi Morokuma (ORCID: https://orcid.org/0000-0001-5995-0017)
- Maki Fukami (ORCID: https://orcid.org/0000-0001-9971-4035)
- Michihiro Kamijima (ORCID: https://orcid.org/0000-0003-0670-8790)
- Koichi Hashimoto
- Shin Yamazaki
- Takahiko Katoh
- Takehiro Michikawa
- Kiyoshi Yoshino
- Mayumi Tsuji
- Chiharu Ota
- Ryoji Shinohara
- Hidekuni Inadera
- Reiko Kishi
- Shuichi Ito
- Children’s Study Group The Japan Environment
- Yasuhiro Takeshima
Institutions
- Toho University (JP)
- Fukushima Medical University (JP)
- Kyushu University (JP)
- Hyogo Medical University (JP)
- Chiba University (JP)
- University of Occupational and Environmental Health Japan (JP)
- National Institute for Environmental Studies (JP)
- Tohoku University (JP)
- Hokkaido University (JP)
- Kyoto University (JP)
- Nagoya City University (JP)
- Tottori University Hospital (JP)
- Kyushu International University (JP)
- National Center For Child Health and Development (JP)
- Harvard Global Health Institute (US)
- University of Toyama (JP)
- University of Yamanashi (JP)
- Kōchi University (JP)
- Yokohama City University (JP)
- Kumamoto University (JP)
- The University of Osaka (JP)
Publication Details
- Journal
- Communications Medicine
- Published
- 2026-05-09
- DOI
- https://doi.org/10.1038/s43856-026-01635-1
- Primary Topic
- Gestational Diabetes Research and Management
- Type
- article
- Field-Weighted Citation Impact
- 0.00