{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,5]],"date-time":"2026-08-05T06:56:07Z","timestamp":1785912967388,"version":"3.56.0"},"reference-count":20,"publisher":"Wiley","issue":"12","license":[{"start":{"date-parts":[[2025,10,15]],"date-time":"2025-10-15T00:00:00Z","timestamp":1760486400000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["obgyn.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Acta Obstet Gynecol Scand"],"published-print":{"date-parts":[[2025,12]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:sec>\n                    <jats:title>Introduction<\/jats:title>\n                    <jats:p>Identifying pregnant smokers is crucial for cessation support and increased fetal surveillance, but some patients may not disclose their smoking. Biochemical markers like breath carbon monoxide (CO) can improve detection, yet the optimal CO threshold for predicting smoking\u2010related risks remains unknown. Our objective was to assess the relationship between smoking, CO levels, and adverse pregnancy outcomes.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Material and Methods<\/jats:title>\n                    <jats:p>This retrospective cohort study analyzed 1\u2009year of pregnancies (2023) in Oxford. Birthweight and adverse outcomes, small for gestational age (SGA), preterm birth (PTB), and extended perinatal mortality (EPM) were compared across CO categories and between self\u2010reported smokers and nonsmokers with CO \u22642 and &gt;2\u2009ppm. Statistical analyses included changepoint analysis, one\u2010way ANOVA, the Cochran\u2013Armitage test for trend, binary logistic regression, and univariate linear regression.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>Of 6963 pregnancies, 5041 (72.4%) had recorded CO levels. The mean gestation at birth was 39\u2009+\u20096\u2009weeks, and the mean birthweight (BW) was 3439\u2009g (560); the mean BW centile was 54.25 (28.00). The prevalence of SGA, PTB, and EPM was 6.7%, 5.0%, and 0.6%, respectively. CO levels were &gt;2\u2009ppm in 11.7% of the cohort, including 5.0% of self\u2010reported non\u2010smokers. Changepoint analysis identified 2\u2009ppm as the threshold for mean birthweight. Above this level, each 1\u2009ppm increase in CO was associated with a 69.35\u2009g decrease in BW and a 3.15\u2010point decrease in BW centile, indicating a dose\u2013response relationship. Above 2\u2009ppm, the odds of adverse outcomes were significantly increased: for SGA, OR 2.05\u20133.37; for PTB, OR 1.50\u20133.21; and for EPM, OR 2.52\u20134.22. Compared to non\u2010smokers with low CO, smokers with high CO had the highest risk of all outcomes. Non\u2010smokers with high CO had increased risks, but not significantly.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>At a threshold of &gt;2\u2009ppm, CO was associated with lower mean birthweight and higher rates of SGA and PTB, with a dose\u2013response relationship. Universal CO testing could help identify and quantify risk in pregnancy.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1111\/aogs.70068","type":"journal-article","created":{"date-parts":[[2025,10,15]],"date-time":"2025-10-15T19:31:21Z","timestamp":1760556681000},"page":"2237-2243","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Carbon monoxide levels, smoking and adverse pregnancy outcomes"],"prefix":"10.1111","volume":"104","author":[{"ORCID":"https:\/\/orcid.org\/0009-0005-8989-7049","authenticated-orcid":false,"given":"Katarzyna","family":"Galka","sequence":"first","affiliation":[{"name":"Nuffield Department of Women's Reproductive Health, John Radcliffe Hospital Oxford University  Oxford UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Michael","family":"Shea","sequence":"additional","affiliation":[{"name":"Fetal Medicine Unit, Women's Centre John Radcliffe Hospital  Oxford UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Christina Y. L.","family":"Aye","sequence":"additional","affiliation":[{"name":"Nuffield Department of Women's Reproductive Health, John Radcliffe Hospital Oxford University  Oxford UK"},{"name":"Fetal Medicine Unit, Women's Centre John Radcliffe Hospital  Oxford UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4462-112X","authenticated-orcid":false,"given":"Lawrence","family":"Impey","sequence":"additional","affiliation":[{"name":"Nuffield Department of Women's Reproductive Health, John Radcliffe Hospital Oxford University  Oxford UK"},{"name":"Fetal Medicine Unit, Women's Centre John Radcliffe Hospital  Oxford UK"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2025,10,15]]},"reference":[{"key":"e_1_2_13_2_1","unstructured":"Office for National Statistics (ONS).Adult smoking habits in the UK: 2023. ONS website statistical bulletin.2024."},{"key":"e_1_2_13_3_1","unstructured":"NHS England.Statistics on Women's Smoking Status at Time of Delivery: England Quarter 4 2023\/24.2024https:\/\/digital.nhs.uk\/data\u2010and\u2010information\/publications\/statistical\/statistics\u2010on\u2010women\u2010s\u2010smoking\u2010status\u2010at\u2010time\u2010of\u2010delivery\u2010england\/statistics\u2010on\u2010womens\u2010smoking\u2010status\u2010at\u2010time\u2010of\u2010delivery\u2010england\u2010quarter\u20104\u20102023\u201024"},{"key":"e_1_2_13_4_1","doi-asserted-by":"publisher","DOI":"10.1186\/s12884-021-03729-1"},{"key":"e_1_2_13_5_1","doi-asserted-by":"publisher","DOI":"10.1177\/1933719114556486"},{"key":"e_1_2_13_6_1","doi-asserted-by":"publisher","DOI":"10.1097\/AOG.0b013e3181ae9e9c"},{"key":"e_1_2_13_7_1","doi-asserted-by":"publisher","DOI":"10.1136\/bmjopen-2021-054535"},{"key":"e_1_2_13_8_1","doi-asserted-by":"publisher","DOI":"10.1111\/j.1365-3016.2003.00520.x"},{"key":"e_1_2_13_9_1","doi-asserted-by":"publisher","DOI":"10.1016\/S0306-4603(00)00070-8"},{"key":"e_1_2_13_10_1","doi-asserted-by":"publisher","DOI":"10.1097\/00124784-200307000-00011"},{"key":"e_1_2_13_11_1","doi-asserted-by":"publisher","DOI":"10.1136\/bmjopen-2018-022089"},{"key":"e_1_2_13_12_1","doi-asserted-by":"publisher","DOI":"10.1378\/chest.117.3.758"},{"key":"e_1_2_13_13_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.rmed.2003.11.018"},{"key":"e_1_2_13_14_1","unstructured":"NHS England.Saving Babies' Lives Version Three: A Care Bundle for Reducing Perinatal Mortality.2023https:\/\/www.england.nhs.uk\/long\u2010read\/saving\u2010babies\u2010lives\u2010version\u20103\/#references"},{"key":"e_1_2_13_15_1","doi-asserted-by":"publisher","DOI":"10.1016\/S0029-7844(97)00103-8"},{"key":"e_1_2_13_16_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.ypmed.2004.04.049"},{"key":"e_1_2_13_17_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.ejogrb.2018.11.020"},{"key":"e_1_2_13_18_1","doi-asserted-by":"publisher","DOI":"10.18332\/tid\/152111"},{"key":"e_1_2_13_19_1","doi-asserted-by":"publisher","DOI":"10.1111\/1471-0528.17395"},{"key":"e_1_2_13_20_1","doi-asserted-by":"publisher","DOI":"10.1136\/adc.86.1.11"},{"key":"e_1_2_13_21_1","doi-asserted-by":"publisher","DOI":"10.1177\/1471082X13504721"}],"container-title":["Acta Obstetricia et Gynecologica Scandinavica"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/obgyn.onlinelibrary.wiley.com\/doi\/pdf\/10.1111\/aogs.70068","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,12,2]],"date-time":"2025-12-02T01:47:18Z","timestamp":1764640038000},"score":1,"resource":{"primary":{"URL":"https:\/\/obgyn.onlinelibrary.wiley.com\/doi\/10.1111\/aogs.70068"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,10,15]]},"references-count":20,"journal-issue":{"issue":"12","published-print":{"date-parts":[[2025,12]]}},"alternative-id":["10.1111\/aogs.70068"],"URL":"https:\/\/doi.org\/10.1111\/aogs.70068","archive":["Portico"],"relation":{},"ISSN":["0001-6349","1600-0412"],"issn-type":[{"value":"0001-6349","type":"print"},{"value":"1600-0412","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,10,15]]},"assertion":[{"value":"2025-04-10","order":0,"name":"received","label":"Received","group":{"name":"publication_history","label":"Publication History"}},{"value":"2025-09-24","order":2,"name":"accepted","label":"Accepted","group":{"name":"publication_history","label":"Publication History"}},{"value":"2025-10-15","order":3,"name":"published","label":"Published","group":{"name":"publication_history","label":"Publication History"}}]}}