{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,11,4]],"date-time":"2026-11-04T20:35:27Z","timestamp":1793824527852,"version":"4.6.1"},"reference-count":24,"publisher":"Wiley","issue":"4","license":[{"start":{"date-parts":[[2022,11,21]],"date-time":"2022-11-21T00:00:00Z","timestamp":1668988800000},"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":["BJOG"],"published-print":{"date-parts":[[2023,3]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:sec><jats:title>Objective<\/jats:title><jats:p>To explore the contribution of pregnancy\u2010related complications on the prevalence of extremely, very and late preterm births in singleton and twin pregnancies. To study the risk of spontaneous preterm birth in twin pregnancies compared with singleton pregnancies.<\/jats:p><\/jats:sec><jats:sec><jats:title>Design<\/jats:title><jats:p>Population\u2010based registry study.<\/jats:p><\/jats:sec><jats:sec><jats:title>Setting<\/jats:title><jats:p>Medical birth registry of Norway and Statistics Norway.<\/jats:p><\/jats:sec><jats:sec><jats:title>Population<\/jats:title><jats:p>Nulliparous women with singleton (<jats:italic>n<\/jats:italic>\u00a0=\u00a0472\u2009449) or twin (<jats:italic>n<\/jats:italic>\u00a0=\u00a08727) births during 1999\u20132018.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>Prevalence rates of pregnancy\u2010related complications for extremely, very and late preterm birth in twin and singleton pregnancies were calculated with 95% confidence intervals. Multivariable logistic regression was applied to assess odds ratios for preterm birth, adjusted for obstetric and socio\u2010economic factors.<\/jats:p><\/jats:sec><jats:sec><jats:title>Main outcome measures<\/jats:title><jats:p>Extremely preterm (&lt;28<jats:sup>+0<\/jats:sup>\u00a0weeks of gestation), very preterm (28<jats:sup>+0<\/jats:sup>\u201333<jats:sup>+6<\/jats:sup>\u00a0weeks of gestation) and late preterm (34<jats:sup>+0<\/jats:sup>\u201336<jats:sup>+6<\/jats:sup>\u00a0weeks of geatation) birth.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>Preterm birth was significantly more prevalent in twin pregnancies than in singleton pregnancies in all categories: all preterm (54.7% vs 6.1%), extremely preterm (3.6% vs 0.4%), very preterm (18.2% vs 1.4%) and late preterm (33.0% vs 4.3%) births. Stillbirth, congenital malformation and pre\u2010eclampsia were more prevalent in twin pregnancies than in singleton pregnancies, but the prevalence of complications differed in the three categories of preterm birth. Pre\u2010eclampsia was more prevalent in singleton than in twin pregnancies ending in extremely and very preterm birth. The adjusted odds of spontaneous preterm live birth were between 19\u2010 and 54\u2010fold greater in twin pregnancies than in singleton pregnancies.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusions<\/jats:title><jats:p>Singleton and twin pregnancies seem to have different pathways leading to extremely, very and late preterm birth.<\/jats:p><\/jats:sec>","DOI":"10.1111\/1471-0528.17344","type":"journal-article","created":{"date-parts":[[2022,11,14]],"date-time":"2022-11-14T05:48:35Z","timestamp":1668404915000},"page":"387-395","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":42,"title":["Different pathways for preterm birth between singleton and twin pregnancies: a population\u2010based registry study of 481\u2009176 nulliparous women"],"prefix":"10.1111","volume":"130","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-4722-1148","authenticated-orcid":false,"given":"Tiril","family":"Tingleff","sequence":"first","affiliation":[{"name":"Faculty of Medicine, Institute of Clinical Medicine University of Oslo  Oslo Norway"},{"name":"Department of Obstetrics Oslo University Hospital  Oslo Norway"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2899-5885","authenticated-orcid":false,"given":"Sari","family":"R\u00e4is\u00e4nen","sequence":"additional","affiliation":[{"name":"Tampere University of Applied Sciences  Tampere Finland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"\u00c5se","family":"Vikanes","sequence":"additional","affiliation":[{"name":"Norwegian Research Centre for Women's Health Oslo University Hospital  Oslo Norway"},{"name":"Gynklinikk Nydalen AS  Oslo Norway"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Leiv","family":"Sandvik","sequence":"additional","affiliation":[{"name":"Department of Obstetrics Oslo University Hospital  Oslo Norway"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4160-3978","authenticated-orcid":false,"given":"Meryam","family":"Sugulle","sequence":"additional","affiliation":[{"name":"Faculty of Medicine, Institute of Clinical Medicine University of Oslo  Oslo Norway"},{"name":"Department of Obstetrics Oslo University Hospital  Oslo Norway"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Gulim","family":"Murzakanova","sequence":"additional","affiliation":[{"name":"Faculty of Medicine, Institute of Clinical Medicine University of Oslo  Oslo Norway"},{"name":"Department of Obstetrics Oslo University Hospital  Oslo Norway"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9970-8401","authenticated-orcid":false,"given":"Katariina","family":"Laine","sequence":"additional","affiliation":[{"name":"Faculty of Medicine, Institute of Clinical Medicine University of Oslo  Oslo Norway"},{"name":"Norwegian Research Centre for Women's Health Oslo University Hospital  Oslo Norway"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2022,11,21]]},"reference":[{"key":"e_1_2_12_2_1","doi-asserted-by":"publisher","DOI":"10.1111\/j.1471-0528.2006.00923.x"},{"key":"e_1_2_12_3_1","doi-asserted-by":"publisher","DOI":"10.1053\/j.semperi.2005.08.002"},{"key":"e_1_2_12_4_1","doi-asserted-by":"publisher","DOI":"10.1097\/01.AOG.0000182578.82926.9c"},{"key":"e_1_2_12_5_1","doi-asserted-by":"publisher","DOI":"10.1007\/s11906-020-01107-4"},{"key":"e_1_2_12_6_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.ajog.2021.07.002"},{"key":"e_1_2_12_7_1","doi-asserted-by":"publisher","DOI":"10.1371\/journal.pone.0063800"},{"key":"e_1_2_12_8_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.ejogrb.2009.02.011"},{"key":"e_1_2_12_9_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.ejogrb.2017.04.035"},{"key":"e_1_2_12_10_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.siny.2010.06.006"},{"key":"e_1_2_12_11_1","doi-asserted-by":"publisher","DOI":"10.1177\/1403494821992894"},{"key":"e_1_2_12_12_1","doi-asserted-by":"publisher","DOI":"10.1111\/aogs.12302"},{"key":"e_1_2_12_13_1","doi-asserted-by":"publisher","DOI":"10.1111\/aogs.12868"},{"key":"e_1_2_12_14_1","doi-asserted-by":"publisher","DOI":"10.1111\/1471-0528.16479"},{"key":"e_1_2_12_15_1","doi-asserted-by":"publisher","DOI":"10.1136\/bmjopen-2019-029908"},{"key":"e_1_2_12_16_1","doi-asserted-by":"publisher","DOI":"10.1002\/uog.17470"},{"key":"e_1_2_12_17_1","doi-asserted-by":"publisher","DOI":"10.1097\/AOG.0000000000004506"},{"key":"e_1_2_12_18_1","doi-asserted-by":"publisher","DOI":"10.2147\/RMHP.S304040"},{"key":"e_1_2_12_19_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.ajog.2020.03.005"},{"key":"e_1_2_12_20_1","doi-asserted-by":"publisher","DOI":"10.1186\/s12884-021-04217-2"},{"key":"e_1_2_12_21_1","volume-title":"National institute for health and care excellence: clinical guidelines. 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