{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,24]],"date-time":"2026-02-24T18:04:05Z","timestamp":1771956245832,"version":"3.50.1"},"reference-count":27,"publisher":"BMJ","issue":"2","license":[{"start":{"date-parts":[[2026,2,24]],"date-time":"2026-02-24T00:00:00Z","timestamp":1771891200000},"content-version":"unspecified","delay-in-days":23,"URL":"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/"}],"funder":[{"DOI":"10.13039\/100018688","name":"Korea Disease Control and Prevention Agency","doi-asserted-by":"publisher","award":["2024-ER1104-01"],"award-info":[{"award-number":["2024-ER1104-01"]}],"id":[{"id":"10.13039\/100018688","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100003710","name":"Korea Health Industry Development Institute","doi-asserted-by":"publisher","award":["RS-2022-KH129953"],"award-info":[{"award-number":["RS-2022-KH129953"]}],"id":[{"id":"10.13039\/501100003710","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100003710","name":"Korea Health Industry Development Institute","doi-asserted-by":"publisher","award":["RS-2025-02213591"],"award-info":[{"award-number":["RS-2025-02213591"]}],"id":[{"id":"10.13039\/501100003710","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["bmj.com"],"crossmark-restriction":true},"short-container-title":["BMJ Open"],"accepted":{"date-parts":[[2026,2,11]]},"published-print":{"date-parts":[[2026,2]]},"abstract":"<jats:sec>\n                    <jats:title>Objective<\/jats:title>\n                    <jats:p>This study aimed to investigate the association between smoking behaviours during early pregnancy and the risk and severity of gestational diabetes mellitus (GDM), with a particular focus on smoking status, smoking intensity and secondhand smoke exposure.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Design<\/jats:title>\n                    <jats:p>Secondary analysis of prospectively collected cohort data.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Setting<\/jats:title>\n                    <jats:p>Multi-centre study conducted in South Korea (Korean Pregnancy Outcome Study) between March 2013 and January 2017.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Participants<\/jats:title>\n                    <jats:p>From 4537 pregnant women initially enrolled, 3457 singleton pregnancies were included after excluding cases with transfer, loss to follow-up, twin pregnancies, miscarriages and pre-existing diabetes mellitus. All participants were women of Korean ethnicity.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Secondary outcome measures<\/jats:title>\n                    <jats:p>Primary outcome was GDM and its subtypes (A1GDM: diet-controlled; A2GDM: insulin-requiring). Secondary outcomes were associations with active smoking (before pregnancy and during early pregnancy), smoking intensity dose\u2013response relationships (pack-years) and secondhand smoke exposure among never-smokers.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>Among 3457 participants, 231\u2009women (6.7%) were diagnosed with GDM (198 A1GDM, 33 A2GDM). Active smoking before pregnancy (adjusted OR (aOR) 3.98, 95% CI 1.58 to 9.30) and during early pregnancy (aOR 9.90, 95%\u2009CI 2.97 to 29.45) were significantly associated with A2GDM, while no significant association was observed with A1GDM. A clear dose-response relationship was observed, with smoking intensity &gt;4 pack-years markedly increasing A2GDM risk (aOR 20.68, 95%\u2009CI 6.75 to 59.39). Detailed pack-year analysis showed 4\u20136 pack-years (aOR 20.57, 95%\u2009CI 5.80 to 65.46) and &gt;6 pack-years (aOR 25.98, 95%\u2009CI 3.21 to 146.45). Among never-smokers, secondhand smoke exposure showed a borderline association with overall GDM risk (aOR 1.33, 95%\u2009CI 0.98 to 1.81).<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>Maternal active smoking before and during early pregnancy, as well as higher smoking intensity, was associated with an increased risk of pharmacologically treated GDM (A2GDM). Although secondhand smoke exposure did not reach statistical significance, the trend suggested a potential association with GDM risk among never-smokers. These findings provide important evidence for public health strategies for prenatal care, as smoking cessation and environmental smoke avoidance during prenatal and early antenatal care in women reduce the risk of gestational diabetes.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1136\/bmjopen-2025-112308","type":"journal-article","created":{"date-parts":[[2026,2,24]],"date-time":"2026-02-24T17:10:40Z","timestamp":1771953040000},"page":"e112308","update-policy":"https:\/\/doi.org\/10.1136\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":0,"title":["Association between smoking behaviours during early pregnancy and the severity of gestational diabetes mellitus: a secondary analysis of prospectively collected cohort data in Korea"],"prefix":"10.1136","volume":"16","author":[{"given":"Ji Hyae","family":"Lim","sequence":"first","affiliation":[{"name":"Smart MEC Healthcare R&D Center, CHA Bundang Medical Center, Seongnam-si, Korea (the Republic of)"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Eun Hui","family":"Joo","sequence":"additional","affiliation":[{"name":"Department of Obstetrics and Gynecology, CHA Bundang Medical Center, Seongnam-si, Korea (the Republic of)"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0009-0001-3699-7450","authenticated-orcid":false,"given":"Hye-Ji","family":"Han","sequence":"additional","affiliation":[{"name":"Department of Obstetrics and Gynecology, CHA Bundang Medical Center, Seongnam-si, Korea (the Republic of)"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jun Sung","family":"Ko","sequence":"additional","affiliation":[{"name":"Department of Obstetrics and Gynecology, CHA Bundang Medical Center, Seongnam-si, Korea (the Republic of)"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Bittna","family":"Chung","sequence":"additional","affiliation":[{"name":"Department of Obstetrics and Gynecology, CHA Bundang Medical Center, Seongnam-si, Korea (the Republic of)"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jin Woo","family":"Kim","sequence":"additional","affiliation":[{"name":"Department of Obstetrics and Gynecology, CHA Bundang Medical Center, Seongnam-si, Korea (the Republic of)"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ju Yeon","family":"Kim","sequence":"additional","affiliation":[{"name":"Smart MEC Healthcare R&D Center, CHA Bundang Medical Center, Seongnam-si, Korea (the Republic of)"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yong Jun","family":"Choi","sequence":"additional","affiliation":[{"name":"Smart MEC Healthcare R&D Center, CHA Bundang Medical Center, Seongnam-si, Korea (the Republic of)"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Su Ji","family":"Yang","sequence":"additional","affiliation":[{"name":"Smart MEC Healthcare R&D Center, CHA Bundang Medical Center, Seongnam-si, Korea (the Republic of)"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"You Jung","family":"Han","sequence":"additional","affiliation":[{"name":"Department of Obstetrics and Gynecology, CHA Gangnam Medical Center, Gangnam-gu, Korea (the Republic of)"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Dong Wook","family":"Kwak","sequence":"additional","affiliation":[{"name":"Department of Obstetrics and Gynecology, Ajou University School of Medicine, Suwon-si, Korea (the Republic of)"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hyun Jung","family":"Lee","sequence":"additional","affiliation":[{"name":"Department of Obstetrics and Gynecology, CHA Bundang Medical Center, Seongnam-si, Korea (the Republic of)"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0710-2582","authenticated-orcid":false,"given":"Hyun Mee","family":"Ryu","sequence":"additional","affiliation":[{"name":"Smart MEC Healthcare R&D Center, CHA Bundang Medical Center, Seongnam-si, Korea (the Republic of)"},{"name":"Department of Obstetrics and Gynecology, CHA Bundang Medical Center, Seongnam-si, Korea (the Republic of)"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"239","published-online":{"date-parts":[[2026,2,24]]},"reference":[{"key":"2026022409101662000_16.2.e112308.1","doi-asserted-by":"publisher","DOI":"10.1016\/j.ogc.2017.02.002"},{"key":"2026022409101662000_16.2.e112308.2","unstructured":"Kunarathnam V , Vadakekut ES , Mahdy H . Gestational diabetes. 2025. Available: https:\/\/www.ncbi.nlm.nih.gov\/books\/NBK545196\/"},{"key":"2026022409101662000_16.2.e112308.3","doi-asserted-by":"publisher","DOI":"10.1097\/AOG.0000000000002501"},{"key":"2026022409101662000_16.2.e112308.4","doi-asserted-by":"publisher","DOI":"10.1016\/j.diabres.2020.108642"},{"key":"2026022409101662000_16.2.e112308.5","doi-asserted-by":"crossref","unstructured":"Roglic G . Global Report on Diabetes. Geneva: World Health Organization, 2016.","DOI":"10.4103\/2468-8827.184853"},{"key":"2026022409101662000_16.2.e112308.6","doi-asserted-by":"publisher","DOI":"10.1016\/j.ijgo.2012.10.032"},{"key":"2026022409101662000_16.2.e112308.7","doi-asserted-by":"crossref","DOI":"10.1007\/s11892-015-0699-x","article-title":"Prevalence of Gestational Diabetes and Risk of Progression to Type 2 Diabetes: a Global Perspective","volume":"16","author":"Zhu","year":"2016","journal-title":"Curr Diab Rep"},{"key":"2026022409101662000_16.2.e112308.8","doi-asserted-by":"crossref","DOI":"10.3390\/jcm9092707","article-title":"Materno-Fetal and Neonatal Complications of Diabetes in Pregnancy: A Retrospective Study","volume":"9","author":"Capobianco","year":"2020","journal-title":"J Clin Med"},{"key":"2026022409101662000_16.2.e112308.9","doi-asserted-by":"crossref","first-page":"2356031","DOI":"10.1080\/14767058.2024.2356031","article-title":"Gestational diabetes mellitus: relationship of adverse outcomes with severity of disease","volume":"37","author":"Karkia","year":"2024","journal-title":"J Matern Fetal Neonatal Med"},{"key":"2026022409101662000_16.2.e112308.10","doi-asserted-by":"crossref","first-page":"184","DOI":"10.1177\/1559827618791980","article-title":"Risk Factors for Gestational Diabetes Mellitus: A Case-Control Study","volume":"15","author":"Amiri","year":"2021","journal-title":"Am J Lifestyle Med"},{"key":"2026022409101662000_16.2.e112308.11","doi-asserted-by":"crossref","DOI":"10.1186\/1471-2458-12-102","article-title":"Heavy smoking during pregnancy as a marker for other risk factors of adverse birth outcomes: a population-based study in British Columbia, Canada","volume":"12","author":"Erickson","year":"2012","journal-title":"BMC Public Health"},{"key":"2026022409101662000_16.2.e112308.12","doi-asserted-by":"publisher","DOI":"10.1007\/BF02333019"},{"key":"2026022409101662000_16.2.e112308.13","doi-asserted-by":"crossref","first-page":"101","DOI":"10.1016\/j.trsl.2017.02.004","article-title":"Smoking and the risk of type 2 diabetes","volume":"184","author":"Maddatu","year":"2017","journal-title":"Transl Res"},{"key":"2026022409101662000_16.2.e112308.14","doi-asserted-by":"publisher","DOI":"10.1038\/s41366-018-0206-y"},{"key":"2026022409101662000_16.2.e112308.15","doi-asserted-by":"crossref","first-page":"1632","DOI":"10.1111\/aogs.13924","article-title":"Impact of smoking on gestational diabetes mellitus and offspring birthweight in primiparous women","volume":"99","author":"Masalin","year":"2020","journal-title":"Acta Obstet Gynecol Scand"},{"key":"2026022409101662000_16.2.e112308.16","doi-asserted-by":"crossref","first-page":"91","DOI":"10.1097\/AOG.0000000000003602","article-title":"Association Between Prenatal Smoking and Gestational Diabetes Mellitus","volume":"135","author":"Bar-Zeev","year":"2020","journal-title":"Obstet Gynecol"},{"key":"2026022409101662000_16.2.e112308.17","doi-asserted-by":"crossref","DOI":"10.1038\/s41598-020-70873-7","article-title":"Prepregnancy smoking and the risk of gestational diabetes requiring insulin therapy","volume":"10","author":"Kim","year":"2020","journal-title":"Sci Rep"},{"key":"2026022409101662000_16.2.e112308.18","doi-asserted-by":"crossref","DOI":"10.3390\/ijerph19084712","article-title":"Passive Smoking and Risk of Gestational Diabetes Mellitus among Nonsmoking Women: A Prospective Cohort Study in China","volume":"19","author":"Na","year":"2022","journal-title":"Int J Environ Res Public Health"},{"key":"2026022409101662000_16.2.e112308.19","doi-asserted-by":"crossref","first-page":"392","DOI":"10.2188\/jea.JE20200055","article-title":"The Korean Pregnancy Outcome Study (KPOS): Study Design and Participants","volume":"31","author":"Choi","year":"2021","journal-title":"J Epidemiol"},{"key":"2026022409101662000_16.2.e112308.20","doi-asserted-by":"crossref","first-page":"972","DOI":"10.1111\/1471-0528.18110","article-title":"First-Trimester Prediction of Gestational Diabetes Mellitus Based on Maternal Risk Factors","volume":"132","author":"Syngelaki","year":"2025","journal-title":"BJOG"},{"key":"2026022409101662000_16.2.e112308.21","doi-asserted-by":"crossref","first-page":"628","DOI":"10.3803\/EnM.2020.948","article-title":"The Clinical Characteristics of Gestational Diabetes Mellitus in Korea: A National Health Information Database Study","volume":"36","author":"Kim","year":"2021","journal-title":"Endocrinol Metab (Seoul)"},{"key":"2026022409101662000_16.2.e112308.22","doi-asserted-by":"publisher","DOI":"10.1542\/peds.2010-3041"},{"key":"2026022409101662000_16.2.e112308.23","doi-asserted-by":"crossref","DOI":"10.3390\/ijerph14121532","article-title":"Prevalence and Determinants of Gestational Diabetes Mellitus: A Cross-Sectional Study in China","volume":"14","author":"Xu","year":"2017","journal-title":"Int J Environ Res Public Health"},{"key":"2026022409101662000_16.2.e112308.24","doi-asserted-by":"publisher","DOI":"10.1111\/j.1365-3016.2011.01221.x"},{"key":"2026022409101662000_16.2.e112308.25","doi-asserted-by":"crossref","DOI":"10.1038\/s41598-018-26412-6","article-title":"Socioeconomic, environmental and lifestyle factors associated with gestational diabetes mellitus: A matched case-control study in Beijing, China","volume":"8","author":"Carroll","year":"2018","journal-title":"Sci Rep"},{"key":"2026022409101662000_16.2.e112308.26","doi-asserted-by":"crossref","first-page":"631","DOI":"10.1093\/ntr\/ntw332","article-title":"Perinatal Biochemical Confirmation of Smoking Status by Trimester","volume":"19","author":"Ashford","year":"2017","journal-title":"Nicotine Tob Res"},{"key":"2026022409101662000_16.2.e112308.27","unstructured":"Korea Disease Control and Prevention Agency . Korea National Health and Nutrition Examination Survey (KNHANES): Trends in current smoking rates, Available: https:\/\/kosis.kr\/statHtml\/statHtml.do?orgId=177&tblId=DT_11702_N001&conn_path=I2 [Accessed 30 Dec 2024]."}],"container-title":["BMJ Open"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/syndication.highwire.org\/content\/doi\/10.1136\/bmjopen-2025-112308","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,2,24]],"date-time":"2026-02-24T17:10:45Z","timestamp":1771953045000},"score":1,"resource":{"primary":{"URL":"https:\/\/bmjopen.bmj.com\/lookup\/doi\/10.1136\/bmjopen-2025-112308"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,2]]},"references-count":27,"journal-issue":{"issue":"2","published-online":{"date-parts":[[2026,2,24]]},"published-print":{"date-parts":[[2026,2]]}},"alternative-id":["10.1136\/bmjopen-2025-112308"],"URL":"https:\/\/doi.org\/10.1136\/bmjopen-2025-112308","relation":{},"ISSN":["2044-6055","2044-6055"],"issn-type":[{"value":"2044-6055","type":"print"},{"value":"2044-6055","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,2]]}}}