{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,26]],"date-time":"2026-06-26T15:53:17Z","timestamp":1782489197369,"version":"3.54.5"},"reference-count":28,"publisher":"BMJ","issue":"5","license":[{"start":{"date-parts":[[2026,5,5]],"date-time":"2026-05-05T00:00:00Z","timestamp":1777939200000},"content-version":"unspecified","delay-in-days":4,"URL":"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/"}],"funder":[{"DOI":"10.13039\/100016275","name":"Seoul National University Bundang Hospital","doi-asserted-by":"publisher","award":["No. 02-2021-0049"],"award-info":[{"award-number":["No. 02-2021-0049"]}],"id":[{"id":"10.13039\/100016275","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100003725","name":"National Research Foundation of Korea","doi-asserted-by":"publisher","award":["RS-2023-00249884"],"award-info":[{"award-number":["RS-2023-00249884"]}],"id":[{"id":"10.13039\/501100003725","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["bmj.com"],"crossmark-restriction":true},"short-container-title":["BMJ Open"],"accepted":{"date-parts":[[2026,4,19]]},"published-print":{"date-parts":[[2026,5]]},"abstract":"<jats:sec>\n                    <jats:title>Introduction<\/jats:title>\n                    <jats:p>The use of CT has increased markedly over recent decades, and this trend is also observed among pregnant women. According to current clinical guidelines, fetal radiation exposure below a threshold of 100 to 200\u2009mGy does not appear to increase the risk of congenital malformations. Although the estimated fetal dose from a maternal abdominopelvic CT examination is generally lower than this range, evidence regarding the risks associated with such relatively low-dose diagnostic exposures during pregnancy remains scarce. This study aims to evaluate the association between abdominopelvic CT exposure during the first trimester of pregnancy and the risk of congenital malformations in infants.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods and analysis<\/jats:title>\n                    <jats:p>We will conduct a nationwide population-based cohort study using the National Health Insurance Service (NHIS) database of South Korea. All live births from 2011 through 2023 will be identified and linked to their mothers. Exposure will be defined as maternal abdominopelvic CT during the first trimester of pregnancy. The primary outcome is major congenital malformations in infants, defined according to the standardised classification system of the European Surveillance of Congenital Anomalies. Secondary outcomes include organ-specific malformations and congenital malformations requiring neonatal intensive care unit admission or corrective surgery. A propensity score-based fine stratification weighting approach will be used to adjust for covariates as potential confounders, and relative risks will be estimated. Prespecified sensitivity analyses will be conducted to assess robustness of the findings.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Ethics and dissemination<\/jats:title>\n                    <jats:p>This study has been approved by the Institutional Review Board of Seoul National University Bundang Hospital (Institutional Review Board No. X-2508-993-902). Informed consent was waived because only anonymised administrative claims data will be used. All analyses will be conducted within the secure NHIS research environment, and no individually identifiable data will be released. The study findings will be disseminated through peer-reviewed publications, scientific conference presentations and communication with regulatory authorities, clinicians and policymakers.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1136\/bmjopen-2025-114426","type":"journal-article","created":{"date-parts":[[2026,5,5]],"date-time":"2026-05-05T13:25:49Z","timestamp":1777987549000},"page":"e114426","update-policy":"https:\/\/doi.org\/10.1136\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":0,"title":["Abdominopelvic computed tomography during pregnancy and the risk of congenital malformations: protocol for a nationwide population-based cohort study in South Korea"],"prefix":"10.1136","volume":"16","author":[{"ORCID":"https:\/\/orcid.org\/0009-0008-2194-4998","authenticated-orcid":false,"given":"Jinhee","family":"Hwang","sequence":"first","affiliation":[{"name":"Department of Applied Bioengineering, Seoul National University Graduate School of Convergence Science and Technology, Seoul, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3412-0863","authenticated-orcid":false,"given":"Jungheum","family":"Cho","sequence":"additional","affiliation":[{"name":"Department of Radiology, Seoul National University Bundang Hospital, Seongnam, Republic of Korea"},{"name":"Department of Radiology, Seoul National University College of Medicine, Seoul, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9508-4280","authenticated-orcid":false,"given":"Hae Young","family":"Kim","sequence":"additional","affiliation":[{"name":"Asan Medical Center Department of Radiology, Seoul, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5508-8634","authenticated-orcid":false,"given":"Seungjae","family":"Lee","sequence":"additional","affiliation":[{"name":"Department of Applied Statistics, Kyonggi University, Suwon, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7877-4450","authenticated-orcid":false,"given":"Young Mi","family":"Jung","sequence":"additional","affiliation":[{"name":"Department of Obstetrics and Gynecology, Seoul National University Bundang Hospital, Seongnam, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6045-765X","authenticated-orcid":false,"given":"Kyoung Ho","family":"Lee","sequence":"additional","affiliation":[{"name":"Department of Applied Bioengineering, Seoul National University Graduate School of Convergence Science and Technology, Seoul, Republic of Korea"},{"name":"Department of Radiology, Seoul National University Bundang Hospital, Seongnam, Republic of Korea"},{"name":"Department of Radiology, Seoul National University College of Medicine, Seoul, Republic of Korea"},{"name":"Interdisciplinary Program in Bioengineering, Seoul National University, Seoul, Republic of Korea"},{"name":"Department of Medical Device Development, Seoul National University College of Medicine, Seoul, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6794-4909","authenticated-orcid":false,"given":"Ji Hoon","family":"Park","sequence":"additional","affiliation":[{"name":"Department of Radiology, University of Pittsburgh Medical Center, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"239","published-online":{"date-parts":[[2026,5,5]]},"reference":[{"key":"2026062608311233000_16.5.e114426.1","doi-asserted-by":"publisher","DOI":"10.1001\/jama.2019.11456"},{"key":"2026062608311233000_16.5.e114426.2","doi-asserted-by":"crossref","DOI":"10.1001\/jamanetworkopen.2019.7249","article-title":"Trends in Medical Imaging During Pregnancy in the United States and Ontario, Canada, 1996 to 2016","volume":"2","author":"Kwan","year":"2019","journal-title":"JAMA Netw Open"},{"key":"2026062608311233000_16.5.e114426.3","doi-asserted-by":"publisher","DOI":"10.1097\/AOG.0b013e318180a505"},{"key":"2026062608311233000_16.5.e114426.4","unstructured":"The Royal College of Radiologists . 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